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Minor League Baseball is in the midst of a Home Run explosion

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2021 is the year of the home run in the minor league system.

Photo Credit: Garrett Spain

In a comment on the midseason prospect list I mentioned how different the offensive environment is in the Double-A South this season versus in previous seasons. That got me thinking about how the other leagues might be playing this season, and I came to some interesting results. This is going to be an extremely statistics-heavy article, but has really changed my views of how offensive players have performed this season and what that could mean in the minor leagues as a whole. Some of the numbers will be explained at the end of the article, so if you don’t understand something scroll to the bottom for a quick glossary.

Starting in Triple-A, it’s obviously the easiest to evaluate because we have more direct news on what the ball looks like. When MLB moved Triple-A to using the same ball as the major leagues it led to immediate effects on the run environment especially with the juiced ball in play. This season the Triple-A levels saw a huge offensive explosion in the first few weeks of the season as they played out their stock of 2019 baseballs. It has since settled to a more manageable level, but the offense is still well above historic levels. Here is a comparison of the power output we’re seeing this season versus years past.

Gwinnett Stripers League Numbers

Stat AAA East 2021 IL 2019 IL 2018 IL 2017 IL 2016
Stat AAA East 2021 IL 2019 IL 2018 IL 2017 IL 2016
AVG 0.247 0.266 0.252 0.257 0.254
OBP 0.333 0.342 0.320 0.324 0.319
SLG 0.415 0.445 0.389 0.394 0.378
OPS 0.748 0.787 0.718 0.718 0.697
ISO 0.168 0.179 0.137 0.137 0.125
HR/G 1.19 1.25 0.80 0.84 0.71
HR/PA 3.15% 3.29% 2.16% 2.25% 1.90%

Overall there is a drop in comparison to 2019, but it’s not as significant as I had imagined and it’s fair to say that hitters are still ruling in Triple-A. Batting average as well as BABIP have returned to and gone below previous seasons, but notably on base percentage is still well above previous seasons. It seems as if the overall industry shift towards three true outcomes plays a significant role here. While at the other three levels you will see significant differences in defensive efficiency, at Triple-A it’s solely a continuation of the pattern towards more walks, strikeouts, and hit batters.

Stripers Peripherals

Stat AAA East 2021 IL 2019 IL 2018 IL 2017 IL 2016
Stat AAA East 2021 IL 2019 IL 2018 IL 2017 IL 2016
K% 24.2% 22.8% 22.0% 21.2% 20.0%
BB% 10.2% 9.3% 8.3% 8.4% 8.0%
HBP% 1.45% 1.29% 1.01% 0.90% 0.84%
BABIP 0.307 0.324 0.312 0.314 0.308
Field % 0.980 0.980 0.982 0.981 0.982

This is not groundbreaking news at all. We knew the league was moving in this direction and we knew it was trickling down into the minor leagues. We were also more than aware that the ball was going to be bouncier and we would see increased offensive output. Where this gets interesting is Double-A and below, where the changes are far more distinct and can’t be explained simply by things we know and industry fads.

Perhaps the most interesting thing to follow for Atlanta Braves fans this season has been the absurd output from Shea Langeliers for the Mississippi Braves. Despite playing in an offensive graveyard Langeliers has put up 19 home runs and power production that we have never really season from a Braves prospect at this level. Regardless of what you learn below Langeliers is worth appreciating as he is among the league leaders in home runs and isolated power, but it does add some context to what he has done.

Mississippi League Numbers

Stat AA South 2021 S LG 2019 S LG 2018 S LG 2017 S LG 2016
Stat AA South 2021 S LG 2019 S LG 2018 S LG 2017 S LG 2016
AVG 0.239 0.243 0.246 0.245 0.249
OBP 0.325 0.318 0.323 0.321 0.321
SLG 0.396 0.366 0.378 0.367 0.363
OPS 0.721 0.684 0.701 0.688 0.684
ISO 0.157 0.123 0.133 0.122 0.114
HR/G 1.06 0.68 0.77 0.67 0.58
HR/PA 2.87% 1.86% 2.07% 1.82% 1.56%

The trend there is very similar to the trend between Triple-A in 2018 and Triple-A now. Triple-A’s increase in that time span was 22% on isolated power and 45% on home run production. The increase from the 2019 Double-A league to the 2021 Double-A league is 28% on isolated power and 54% on home run production. Those are massive numbers, and it’s not at all what any of us would have expected to see. The Southern League was notorious for poor offensive performance and is now performing nearly as absurdly as the Triple-A level. We’re also seeing the standard drop in batting average and lift in on base percentage.

Mississippi Peripherals

Stat AA South 2021 S LG 2019 S LG 2018 S LG 2017 S LG 2016
Stat AA South 2021 S LG 2019 S LG 2018 S LG 2017 S LG 2016
K% 25.9% 22.8% 23.0% 21.5% 20.3%
BB% 9.7% 8.8% 9.2% 9.1% 8.7%
HBP% 1.75% 1.29% 1.21% 1.15% 1.09%
BABIP 0.307 0.31 0.31 0.305 0.308
Field % 0.975 0.978 0.977 0.98 0.978

The peripherals here are not linear like Triple-A due to the 2019 drop in strikeouts and walks, but overall the trend is the same and was kicked into overdrive for 2021. While many Triple-A players found themselves at alternate sites and on big league rosters in 2020 Double-A players often did not. The gap here isn’t that big, but it will increase quickly as we get towards lower levels and into league with much lower percentages of guys who had formal training from the organization in 2020.

Rome League Numbers

Stat High-A East SAL 2019 SAL 2018 SAL 2017 SAL 2016
Stat High-A East SAL 2019 SAL 2018 SAL 2017 SAL 2016
AVG 0.241 0.239 0.249 0.250 0.250
OBP 0.333 0.316 0.315 0.317 0.319
SLG 0.396 0.362 0.379 0.369 0.372
OPS 0.729 0.678 0.694 0.686 0.691
ISO 0.155 0.123 0.130 0.119 0.122
HR/G 0.96 0.65 0.71 0.61 0.62
HR/PA 2.51% 1.76% 1.95% 1.65% 1.68%

High-A Peripherals

Stat High-A East FSL 2019 FSL 2018 FSL 2017 FSL 2016
Stat High-A East FSL 2019 FSL 2018 FSL 2017 FSL 2016
K% 27.1% 22.7% 21.3% 21.5% 19.9%
BB% 9.8% 8.2% 8.4% 8.1% 8.5%
HBP% 1.51% 1.35% 1.35% 1.36% 1.17%
BABIP 0.314 0.309 0.315 0.315 0.308
Field % 0.973 0.976 0.978 0.976 0.974

This is really hard to parse here, and you can clearly see I had to make a choice I didn’t want to make really. Rome has always been a Low-A organization, and comparing numbers across levels is not really fair. The South Atlantic League was all split up and teams are playing in different stadiums, so I can’t really draw too many conclusions off of the power inputs. Comparing the High-A East to the Florida State League in that regard would also have been completely unfair as that league suppresses power significantly and the numbers would have overstated the difference. If you’re curious, the Florida State League hovered between an ISO of .106 and .116, a HR/G of .53 to .59, and a HR/PA of 1.44% to 1.61%. The league annihilated power production and it wasn’t fair to make that conclusion, so I tried to get a little closer from a stadium standpoint for those numbers. We can also draw some Carolina League comparisons, where the ISO range was .117 to .129, HR/G ranged from 0.60 to 0.69, and HR/PA ranged from 1.62 to 1.87%. On the peripherals they’re not as stadium dependent so I went back to using the Florida State League and you can see the stark differences. None of the three leagues showed much of a trend other than increasing strikeouts, so it’s likely that aspect of the industry trend has not yet made it’s way down to being taught at that level. This is again a flawed section, but it does highlight the drastic power differences from what we’ve seen from Rome players in the past and contextualizes what we’ve seen from Jesse Franklin on offense and Jared Shuster and Darius Vines on the mound. Some of these home runs likely don’t leave the yard in most seasons and they could all be having drastically different seasons if they were not.

Augusta League Numbers

Stat Low A East SAL 2019 SAL 2018 SAL 2017 SAL 2016
Stat Low A East SAL 2019 SAL 2018 SAL 2017 SAL 2016
AVG 0.242 0.239 0.249 0.250 0.250
OBP 0.338 0.316 0.315 0.317 0.319
SLG 0.380 0.362 0.379 0.369 0.372
OPS 0.718 0.678 0.694 0.686 0.691
ISO 0.137 0.123 0.130 0.119 0.122
HR/G 0.81 0.65 0.71 0.61 0.62
HR/PA 2.15% 1.76% 1.95% 1.65% 1.68%

Low-A Peripherals

Stat Low A East SAL 2019 SAL 2018 SAL 2017 SAL 2016
Stat Low A East SAL 2019 SAL 2018 SAL 2017 SAL 2016
K% 25.7% 24.2% 23.3% 22.0% 21.6%
BB% 10.9% 8.7% 7.5% 7.5% 8.0%
HBP% 1.87% 1.60% 1.49% 1.49% 1.38%
BABIP 0.321 0.310 0.316 0.316 0.313
Field % 0.968 0.973 0.971 0.973 0.973

This is, again, an imperfect comparison because the South Atlantic League was split up. What it does do is show how hideous the level has been this season and still continues the trend of increased power production at each level. While the team may be so bad they can’t capitalize on the swell in production, it still seems to be there. There’s also a continuation of the strikeout trend and an obvious sign in the hit batter and walk rates that pitchers can’t take a year off and expect to be good. The league-wide BABIP increase could be a sign of poorer defense, but it’s worth mentioning it could just be a fluctuation. The International League saw a 12 point jump in BABIP with the juiced balls, but the other Triple-A League — Pacific Coast League — only saw a 2 point jump which is well within the bounds of year-to-year fluctuation. That said, there is a significant Low-A bump across all leagues in BABIP so it may be a genuine sign of defense struggles. I know a .968 fielding percentage versus a .973 fielding percentage doesn’t seem THAT big, but that’s a 19% increase in the rate of errors being made.

All of this information is fine, but again there was some major shifting in the landscape of baseball and it’s very possible that the Braves minor league franchises all just landed in more hitter-friendly leagues right? All three of the lower levels were in notoriously pitcher-friendly leagues so seeing an increase in performance should be expected. Well, stick around for a bit because it’s about to get even more interesting.

Let’s start with Triple-A because it’s exactly what we expect. I’m not bothering with a chart because it follows exactly with the one at the top of this page, I’ll just explain. Everything is down on offensive production, but it’s still well above where it was from 2016 to 2018. Strikeouts, walks, and hit batter rates have all gone up for at least the fourth consecutive season and my assumption is that goes even further back. This is just a baby version of Major League Baseball. Let’s move on to Double-A, where for the most part the leagues stayed fairly consistent. And oh boy are these numbers fun.

Double-A All Levels

Stat AA 2021 AA 2019 AA 2018 AA 2017 AA 2016
Stat AA 2021 AA 2019 AA 2018 AA 2017 AA 2016
AVG 0.243 0.243 0.253 0.255 0.253
OBP 0.328 0.317 0.327 0.326 0.322
SLG 0.403 0.371 0.388 0.384 0.378
OPS 0.731 0.688 0.715 0.711 0.700
ISO 0.160 0.129 0.136 0.13 0.124
HR/G 1.1 0.75 0.81 0.76 0.69
HR/PA 2.95% 2.04% 2.18% 2.05% 1.83%
K% 25.6% 23.2% 21.8% 20.4% 20.2%
BB% 9.8% 8.7% 8.9% 8.7% 8.5%
HBP% 1.58% 1.24% 1.18% 1.11% 1.03%

That is quite a lot. Let’s break it down. Like we saw with the Double-A south power production is significantly up. Home runs per game are up 44% over 2019 and Home runs per plate appearance are up 45%. Isolated power is up 24%. Recall from earlier, the increase from the last normal Triple-A season to now is 45% in home runs and 22% in Isolated Power. Double-A players are hitting the ball out of the park at an unprecedented rate. A valid argument here is that guys took a year off so they’re older than normal and older players tend to be stronger and more physically developed. The average age in 2019 was 23.9 for hitters and 24.3 for pitchers and the average age in 2021 is 24.2 for hitters and 24.7 for pitchers. So not that big of a difference. Interestingly, while at the single league level walks were trending up significantly they have not overall in Double-A until this season. Strikeouts and hit batters continue to pile up at an alarming rate, but the walks are seeing the first major jump just now after a layoff.

High-A All Leagues

Stat A+ 2021 A+ 2019 A+ 2018 A+ 2017 A+ 2016
Stat A+ 2021 A+ 2019 A+ 2018 A+ 2017 A+ 2016
AVG 0.240 0.245 0.253 0.255 0.257
OBP 0.329 0.321 0.327 0.324 0.328
SLG 0.398 0.366 0.38 0.381 0.381
OPS 0.727 0.686 0.707 0.705 0.709
ISO 0.158 0.121 0.127 0.126 0.124
HR/G 1.03 0.64 0.69 0.68 0.66
HR/PA 2.73% 1.75% 1.84% 1.81% 1.75%
K% 26.6% 23.5% 22.1 22.0% 20.5%
BB% 10.2% 8.8% 8.7% 8.3% 8.7%
HBP% 1.60% 1.39% 1.31% 1.24% 1.21%

Four years of stagnant-to-decreasing offensive production and then all of the sudden record home run numbers. You know where I’m going with all of this. I’m going to be annoying and not say it yet. It’s interesting again that we see this trend of walks not really increasing that much while hit by pitch rates are skyrocketing. I don’t know what this means, I just think it’s funny and I like that the league is becoming more conducive to my Ray-Patrick Didder fourth outfielder campaign becoming reality. I miss you Diddy. Anyways, a 10% walk rate is absurd and it’s only getting worse when we get to the next chart, so to ease the disgust you’ll be feeling in a few minutes I’m going to drop in a video of Tom Glavine’s Game 6. Enjoy your break.

Anyhoo, the strikeout rate trend here is absurd and a lot of that bump is the long layoff for these hitters. All of the lower levels had fairly similar numbers over the previous four years, but the gap between the pitching at Double-A and A ball has grown tremendously. Also, five consecutive seasons of batting average going down is both impressive in its consistency and concerning in its implications. Warning, if bad baseball makes you sick you may want to skip this next chart.

Low-A All League

Stat A- 2021 A- 2019 A- 2018 A- 2017 A- 2016
Stat A- 2021 A- 2019 A- 2018 A- 2017 A- 2016
AVG 0.243 0.239 0.250 0.250 0.249
OBP 0.342 0.319 0.320 0.318 0.318
SLG 0.386 0.358 0.376 0.363 0.363
OPS 0.728 0.678 0.696 0.681 0.681
ISO 0.132 0.119 0.126 0.114 0.114
HR/G 0.84 0.62 0.66 0.66 0.55
HR/PA 2.18% 1.66% 1.80% 1.77% 1.47%
K% 26.2% 23.7 22.9 22.1% 21.7%
BB% 11.4% 9.1% 8.2% 8.2% 8.1%
HBP% 1.88% 1.54% 1.66% 1.43% 1.28%

Let’s start with a caveat. The Low-A Southeast League is using an electronic strike zone this season, and it has not been perfectly dialed in to the shortcomings of Low-A pitchers. The walk rate in that league is 12.8% and it’s sub 11% in other leagues. I say sub 11% like that’s not appalling to my soul, but at least it’s not 12.8%. Also about the Low-A Southeast League - That used to be the Florida State League. The Florida State League with less able Low-A players should be an offensive wasteland. Spoiler: It’s not. As a High-A league it produced a .111 ISO and 1.52% home run rate over four seasons. As a Low-A league the current league ISO is .134 and the home run rate is 2.00%. The league OPS is over .700 at .713. It’s playing like a perfectly normal and even somewhat offense friendly league especially for the Low-A level. In fact that’s a higher Low-A OPS, ISO, and home run rate than any produced by the South Atlantic League or Midwest League in our sample. Overall the strikeout rate here is appalling, but we again see the significant increase in power. Just as a rundown of the increases from 2019 to 2021

Double-A - 24% ISO increase, 45% HR rate increase

High-A - 31% ISO increase, 56% HR rate increase

Low-A - 19% ISO increase, 31% HR rate increase

All Three Levels - 24% ISO increase, 43% HR rate increase

Here are your numbers for all three levels

Non-Triple A Peripherals

Stat 2021 A-AA 2019 A-AA 2018 A-AA 2017 A-AA 2016 A-AA
Stat 2021 A-AA 2019 A-AA 2018 A-AA 2017 A-AA 2016 A-AA
K% 26.1% 23.5% 22.3% 21.5% 20.8%
BB% 10.5% 8.9% 8.6% 8.4% 8.4%
HBP% 1.70% 1.39% 1.29% 1.26% 1.17%
BABIP 0.317 0.311 0.316 0.315 0.313
Field % 0.972 0.975 0.975 0.976 0.975

There is a slight trend up in overall walks that didn’t show up at any individual level, but the larger sample size displays fairly clearly. It’s not major, but that layoff made it a big deal and I expect within the next three years that will come down somewhat though it will never be where it was before. The hit by pitch rates are going absolutely haywire with an increase since 2016 of 45%. Of course, strikeout rates also jumped and were aided by the layoff. The average strikeout rate increase of the previous four years was 0.9%, and although it seemed to be accelerating if you take it at a linear increase that would put it at 26.2% by 2022 had there been normal baseball. So it’s really just pushed the timeline forward a season. There is a high water mark in BABIP, but I’m hesitant to say that’s due to the layoff. It’s .001 above the second highest mark. The real outlier is fielding percentage, and look I know we hate it but going minors wide from .975 to .972 is not a small shift. Now. Let’s get to the chart that matters. Looking league-by-league is fine, but with realignment it skews some of the overall information. A look at every level will make this more balanced, and the results are clear.

Non-Triple-A performance

Stat 2021 A-AA 2019 A-AA 2018 A-AA 2017 A-AA 2016 A-AA
Stat 2021 A-AA 2019 A-AA 2018 A-AA 2017 A-AA 2016 A-AA
AVG 0.242 0.242 0.252 0.253 0.253
OBP 0.333 0.319 0.325 0.324 0.323
SLG 0.396 0.365 0.381 0.38 0.374
OPS 0.729 0.684 0.706 0.704 0.697
ISO 0.153 0.123 0.129 0.127 0.121
HR/G 0.67 0.67 0.72 0.70 0.63
HR/PA 2.61% 1.82% 1.94 1.88% 1.69

The first conclusion you’ll likely come too is that the ball is different, but I’m not outright saying that MLB juiced the baseballs across the board. For what it’s worth, this is a small sample of seasons, and if 2019 was an outlier then you had three straight season of increasing power production across the levels. 2021 is a weird season, and every single statistical category has been an outlier. Pitchers command has clearly suffered based on walk rates and hit batter rates, so by an extension of that logic they should be leaving more balls over the plate as well. Those balls get hit harder. I also don’t include home run per fly ball rates because it would be quite difficult to actually get that information and I don’t have like two weeks to dedicate to just this topic. Overall, the takeaway is that offensive production across the board is up so if your prospect is having a career power year maybe it’s time to reflect on what that really means. So I’m not saying that major league baseball has juiced the balls.

But like.....they could have. The increase here is sharp. I mentioned the 43% increase in HR/PA, but what if we break that down further. Once you exclude the rises in walks and hit batters that naturally take away from home run opportunities you’re left with an even bigger difference.

HR/AB - Low A to Double-A

2016 - 1.90%

2017 - 2.11%

2018 - 2.19%

2019 - 2.06%

2021 - 3.01% - That’s 46% increase. Not a huge difference between 43% increase in HR/PA, but it shows an even bigger gap. Now let’s extend that. What about HR/Batted Ball. Now we take strikeouts out of the equation and look at simply the balls in play that had an opportunity to leave the yard

2016 - 2.45%

2017 - 2.75%

2018 - 2.89%

2019 - 2.77%

2021 - 4.26%

That is a 54% increase over the numbers produced in 2019. That is monstrous and a complete landscape shift in minor league baseball. In just 60% of the games the Minor Leagues in 2021 are 89% of the way to 2019’s home run total. At the current pace, the entire minor leagues would clear 10000 home runs, when in our sample they have never cleared 9000. On their current pace they would hit 1,640 more home runs in 2021 than the high water mark of 2018, while playing a 120 game schedule rather than a 144 game schedule. 1,640 more home runs in 1700 fewer games. It is hard to explain how that could happen simply by a shift in the industry and a pandemic layoff. While the increase in strikeout rates, walk rate, and hit batter rates is only a year ahead of schedule, if you exclude the 2019 season then 2021’s power production is 3 years ahead of the curve. If you include 2019 then 2021 is at least five years ahead of the curve. No other statistical category increased nearly that much, and every single one that did increase did so in a way that reflects lower quality baseball. More strikeouts, more walks, more hit batters, and more errors are all signs of inexperienced players. More home runs is the exact opposite story. Hitting home runs takes development and ability.

We do have to look at other possibilities. Some of this could be attributed to having more filler on the roster, though that is likely a weaker argument given reduced roster sizes. It is, however, true that innings are being limited more and fringy players are getting more innings. We’re also seeing a record number of independent league players being poached. Can that affect the sample enough to cause this large of a discrepancy? I lean towards no. Let’s do a quick numbers break down for HR/FB. I said I can’t do league rates, but Fangraphs has a convenient leaderboard with filters that I can use. So, using the top 100 or so pitchers by innings in each league to filter in only the guys teams want giving them innings, here are the median HR/FB rates at each level. Now, caveats before you read. Doing median isn’t the most accurate way, especially when comparing across different leagues like with Triple-A where they are vastly different run environments. I’m limited on the information I have access too, and this is the best solution I have to the problem. Given that it shows consistency with my previous findings, I thought it fitting to include even if I don’t give it the same weight I do other statistics here.

All Levels HR/FB Median

League HR/FB League HR/FB Level HR/FB Level HR/FB
League HR/FB League HR/FB Level HR/FB Level HR/FB
AAA East 2021 14.3% A+ East 2021 12.8% AAA 2021 14.8% A+ 2021 10.8%
International 2019 14.1% Carolina 2019 6.6% AAA 2019 14.8% A+ 2019 6.8%
International 2018 8.5% Carolina 2018 6.6% AAA 2018 9.1% A+ 2018 7.1%
International 2017 8.3% Carolina 2017 8.1% AAA 2017 9.1% A+ 2017 7.4%
International 2016 8.2% Carolina 2016 7.0% AAA 2016 8.5% A+ 2016 7.2%
AA South 2021 12.8% A- East 2021 9.7% AA 2021 12.1% A- 2021 10.2%
Southern 2019 7.3% Sally 2019 7.2% AA 2019 8.5% A- 2019 6.7%
Southern 2018 8.3% Sally 2018 8.2% AA 2018 8.7% A- 2018 7.1%
Southern 2017 6.8% Sally 2017 7.0% AA 2017 8.2% A- 2021 6.8%
Southern 2016 6.6% Sally 2016 6.8% AA 2016 7.4% A- 2019 6.3%

Overall, the shape of this holds well with what has been put out so far. At every single level that holds a current Braves affiliate the high mark for median HR/FB rate is 2021. For most leagues it’s far and away the case, though with Low-A East the number is fairly similar to that posted in 2019. Keep in mind the sample here is only 100 players per league, so this kind of fluctuation season to season has a much larger chance of happening. Once you extend it to all leagues in a given level the results are almost exactly in line with above numbers. Look at the jump from 2018 to now in Triple-A - 9.1% to 14.8% that represents an increase of 63% over the last season with a normal ball. That is even more inflated than what we’ve seen at other levels, but again with the caveat of median, a different sample of players given the innings limits, and the weirdness of having drastically different offensive leagues I can’t call this reliable. Double-A features a smaller but more consistent increase of 42.4%, which is almost exactly in line with the numbers we’ve seen with regards to overall home run rate production. High-A gets weird as well with the 59% increase in HR/FB rate, and it’s hard to trust the actual number. In previous seasons you had major outliers in the California League and the Florida State League on opposite ends of the spectrum with both having obvious affects on the sample reliability. Low A also has seen a major shift in the way the leagues are structured, and you still have an increase in median HR/FB rate of 52%. Overall the individual numbers aren’t that important, but we can fold this in the general pattern we’ve seen.

Now, it is still possible that the trend holds. Looking at that 15% increase from 2016 to 2018, if a similar 15% increase happened every two years you would have a HR/PA of 25.6% by 2022. Like stated before the pandemic seems to have shifted trends forward by a season so this is possible. Figuring out if 2019 was a fluke will simply take more data to understand.

Low-A to Double-A

Year K% BB% HR/PA
Year K% BB% HR/PA
2021 26.1% 10.5% 2.61%
2019 23.5% 8.9% 1.82%
2018 22.3% 8.6% 1.94%
2017 21.5% 8.4% 1.89%
2016 20.8% 8.4% 1.69%
2015 19.5% 8.2% 1.47%
2014 19.8% 8.4% 1.75%
2013 20.0% 8.8% 1.79%
2012 19.5% 8.7% 1.85%
2011 19.7% 8.6% 1.93%
2010 19.7% 8.5% 1.75%
2009 19.2% 8.6% 1.65%
2008 19.0% 8.7% 1.90%
2007 18.7% 8.8% 1.97%
2006 19.1% 8.8% 1.81%
2006 1.81%
2007 1.97%
2008 1.90%
2009 1.65%
2010 1.75%
2011 1.93%
2012 1.85%
2013 1.79%
2014 1.75%
2015 1.47%
2016 1.69%
2017 1.89%
2018 1.94%
2019 1.82%
2021 2.61%

Okay that’s a lot. Let’s see a line graph of those home run rates

That is a substantial and unprecedented change, at least over a full 15 season sample. Prior to the 2019 to 2021 gap there had never been an increase of more than .22% from 2015 to. The two year increase peak is from 2015 to 2017, when it went from 1.47% to 1.89%. A two year change of 1.82% to 2.61% is far more drastic than that, and unlike the previous didn’t come at the result of a historically low offensive output. From the strikeout and walk standpoint the trends don’t extend past 2015. Here’s what I will say. From 2015 to 2018 there was an increase of 32% in home run rate. While that is fairly far short of the 43% we’ve seen in recent years, there is certainly a way to argue it is just simple league progression. This would also imply that 2019 is an outlier, but based on the history of the minor leagues that isn’t really clear. There’s a precedent for offense to increase for a few seasons before cratering. Over this entire 15 year window the highest the home run rate ever jumped was 1.97%, extremely far from the 2.61% rate we’ve seen this season.

There are two big factors to look at that could certainly be impacting the performance overall. One, to a lesser extent, is the lack of April. Typically in April offensive performance is more limited, like for example at the major league level this season where the league ISO was .157 and has since been .167. That’s not going to cause a major shift, but it would have pulled the numbers down slightly. We also have to look at the crackdowns on grip enhancing substances. While this has been discussed extensively at the major league level the same is happening in the minor leagues and it does affect offensive production. To what extent that is true is unclear because I just don’t have the month-by-month splits, but it certainly stands to reason that it has led to increased offense over previous seasons. The most innocent explanation to all of this is that the combination of the sticky stuff memo, the lower pitching talent across the minor leagues, and the trend of the league towards more home runs has led to an unprecedented offensive explosion. Look at the walk rates and they have a similarly drastic increase. That points to a definitive lack of command in comparison to previous years, even excluding the weird Low-A Southeast League. Strikeouts and hit batters have stayed roughly on the same course, but walks are completely out of this universe. This absolutely contributes to the home run surge as discussed before with more balls being left over the meat of the plate where they would be hit harder on average. It’s entirely impossible to gauge the affect of this, especially when again considering the lesser offensive ability that would pull the numbers in the opposite direction. It’s clear however that more balls over the plate with less spin on them due to the substance crackdowns should help move the needle towards home runs even if lower offensive skill will pull it in the opposite direction.

What I can say for sure is that MLB did it with the major league ball, and now suddenly the year they take control of the minor leagues every single minor league level is showing an increase in production over the previous year. Not just every level, but every single league, and by nearly the exact same rate as the increase in production the current ball provided over the minor league ball in Triple-A. We know the ball is juiced that the Triple-A level and the situation with many Triple-A players is comparable to the lower levels to make it easier to gauge how talent level impacts the production. What we have at Triple A is a similarly drastic increase in walks, hit batters, and strikeouts from 2018, indicating that perhaps talent level, no April, and the sticky stuff is not enough to shift the league. Walks went from 8.6% to 10.2%, hit batters from 1.03% to 1.37%, and strikeouts from 21.4% to 23.7%. The walk and hit batter rates especially are right in line with the command quality we’ve seen from lower levels and cast doubt on the idea that leaving more balls over the plate and having league-wide lower spin rates is enough to affect the numbers this much. It took a juiced ball to see the offensive fireworks in Triple-A. It’s absolutely worth asking questions and it’s more likely than not that something is different, though it could simply be explained away by the talent pool.

It’s also worth wondering if this would even be a reasonable move to think MLB would make. Obviously, MLB doesn’t have a history of making good decisions, but it’s still interesting. Why would baseball want to make a move like that when it was widely criticized at the MLB level. Here’s the thing. While the super ball at the Major League Level was a clear step too far, bringing that sort of ball performance to the minor league level wouldn’t be an outrageous thing. Minor League run environments are just a different demon. Look at MLB numbers. The league ISO in 2018 prior to the ball change was .161. The average HR/FB rate was 12.7%, and the HR/PA was at 3.0%. The trend of high strike out levels could quickly make minor league baseball a hard product to market, but if you can bring power production closer in line with the major league level it makes games more entertaining. The balance in the minor leagues is clearly and drastically swinging towards pitchers, and livening the ball up like this would absolutely make it a more even playing field. Baseball needs to be fun, especially at the minor league level which is easily the most accessible for getting young fans into the game.

I’m not going to say they changed the minor league baseball; I’ll leave that to each reader’s imagination. What we don’t have is two balls to compare and test to see if there are any physical changes. Without that there is simply no definitive way to say the ball has been changed intentionally or otherwise. We do have the numbers in front of us to hint that something has flipped, but whether that is the natural progression of the game combined with lower talent pitching, or whether it’s indicative of tampering isn’t clear. If it came out tomorrow that the minor league ball have been juiced a bit, there’s not a single person reading this that would be surprised. MLB does things for their own reasons and sometimes, like this, it may actually make the on field product more enjoyable. I’m interested to see how the last month affects these numbers and if fatigue takes a bite out of them. We will also have to wait it out and see if these numbers carry over into the future. Consecutive seasons of inflated home run numbers would obviously be a sign of something amiss, even more than what we already have. Here is your evidence. Do with it as you please. And remember kids, when Shea Langeliers is up to bat in Pensacola, Florida, you should probably bring a helmet.

Stat Glossary

ISO - Isolated Power. It’s just slugging percentage (SLG) minus batting average (AVG). It’s meant as a way to capture how often a player is producing extra bases with power

BABIP - Batting average on balls in play. Calculated as (Hits - Home Runs) / (At bats - Home Runs - Strikeouts). Meant to show how often batted balls are converted into hits.

HR/FB - Home runs per fly ball. If you can find a place I can get league wide batted ball numbers please do send it. I am not about to go through every single player in each league for five years to see how many fly balls they hit. This would be the most accurate way to frame this but the numbers aren’t really at my disposal.

HR/G - Home runs per game. Pretty self explanatory

HR/PA - Home Runs per plate appearance. Also say it home run rate. I use it as a percentage. HR/G and HR/PA are fairly redundant. HR/PA is more accurate, in fact HR/AB is even more accurate for these purposes. I included HR/G because it’s easier to understand conceptually. We know a home run per game is good just from basic watching, but a 2% home run rate isn’t as natural to comprehend even if it’s more accurate.

The reason I say home runs per at bat is more accurate is because walks and hit batters don’t actually provide the opportunity to hit the baseball. I just wanted to make sure each statistic used a common denominator of plate appearances.