Jace Peterson had a pretty interesting season for the Braves in 2015, winning the starting second base job after impressing in Spring Training with the bat and posting a .324/.410/.397 triple slash.
With that, plus an exceptional start to the regular season, Peterson proceeded to start in 137 games for the Braves over the course of the season and finished the year as a 1.1 WAR player with a .239/.314/.335 triple slash and 80 wRC+. While these numbers are far from impressive, for the most part Peterson played a solid defensive second base, and occasionally ran into a hot streak here and there at the plate.
Today, I just wanted to take a bit of a look at what Peterson's season was like, dive into the stats a little bit, and look ahead to what we can expect from Peterson next season.
At The Plate
If you take a look at the gray shaded portion of this graph, you'll get a pretty good indication of what Peterson's season was like in general. While this shows just his batting average, most of the other general statistics have a similar shape. It seems that Peterson took advantage of the fact that pitchers were learning how to attack him, in addition to an inflated BABIP to take advantage for much of the first half.
Through the months of May and June, Peterson posted a .272/.357/.401 triple slash thank in part to a .323 BABIP. From July through the rest of the season, Peterson's numbers look significantly worse: a .212/.281/.297 slash and a .271 BABIP.
So what happened that caused such a dramatic drop off? Well, for the most part I think Peterson's hot streak through May and June was just that: a hot streak. And at some point, it had to come to an end. Pitchers didn't start attacking him much differently. In fact, lefties came after him with fastballs on the first pitch at a higher rate during the latter half of the season than through May/June. Right-handed pitchers began going at Peterson with breaking/offspeed offerings on first pitch a bit more, but it was a minute difference (37 percent breaking/offspeed on first pitch during the first half, and 40 percent breaking/offspeed during the second half).
The table below shows that Peterson's exit velocity was pretty consistent throughout the season as well, aside from a brief spike in July and a drop-off near the end of August.
The one obvious weakness in Peterson's game came against breaking pitches, where he whiffed on 38 percent of the pitches that he swung at — significantly above the league average.
Here's how Peterson fared throughout the season against each individual pitch type:
He's clearly hitting fastballs better than any other pitch type, while swinging and missing at changeups, sliders and curves at a pretty substantial rate. This shouldn't come as much of a surprise, given that this was Peterson's first full season as a Major League player.
During the middle of July, I had the chance to ask Jace a bit about the adjustments he was seeing from opposing pitchers and the adjustments he was making in return. According to him, there wasn't much of anything different going on, it was more about him having the discipline to swing at good pitches.
Here's a bit of the interview:
Are pitchers attacking you any differently now than they were at the beginning of the season?
"No I think it’s a matter of swinging at your pitch, swinging at good pitches, swinging at strikes and trying to hunt fastballs. Not really getting out of your plan. And the more you can stick to that and swing at good pitches I think no matter what they’re throwing you should be alright."
Have you noticed any difference with Freddie Freeman out of the lineup?
"Yeah definitely when you have him in the lineup you definitely get some different pitches because he’s a threat behind you. So anytime you’re missing one of the best hitters in the game in your lineup it’s definitely going to make a difference so we definitely can’t wait to have him back."
Do they try and pitch around you more than they normally do?
"Maybe a little bit, definitely throw some more stuff to try to get you out, knowing that when we’re on they’ve got to worry about us maybe stealing a bag and giving him a fastball and letting him really hit it. Not worrying about having to pitch around him in the lineup is definitely big."
So it sounds like there was a bit of an adjustment there; whether that stems from the fact that Freeman was out of the lineup or because pitchers were changing their approach with Peterson is still up for some debate. I'd argue it's a mix of both.
Unsurprisingly though, Peterson — as well as others, most notably Cameron Maybin — did struggle when Freeman left the lineup for about a month there starting on June 17. Leading up to that (from April 6 to June 17) Peterson was plugging along with a .279/.350/.374 slash. Once Freeman left the lineup, Peterson's numbers immediately tanked. From June 18 to July 24 (the period Freeman missed) his triple slash fell to .179/.273/.283. That's pretty substantial, and while it's obviously a small sample, you'd be hard pressed to call that simply a coincidence.
Before we move away from the batting, I feel like it is important to talk about Peterson's platoon splits. After the 2014 season, when Baseball America rated Peterson the No. 10 prospect within the Padres farm system, this is what was said about his ability to hit lefties (emphasis is mine):
His simple, quick, lefthanded stroke and on-base ability will allow his hit tool to play near average, though his power will play only to the gaps. He sees the ball well against lefthanders and should not require a platoon partner. Peterson played plenty of second and third base at Triple-A and in the Arizona Fall League, and his average range, speed and arm strength would play better at those position than at shortstop.
Unfortunately, that bolded portion didn't prove to be the case this season, as Peterson hit just .190/.234/.276 against lefties in 114 plate appearances, compared to a .251/.332/.350 line against right-handers in 483 plate appearances.
In The Field
Peterson was generally regarded as a solid defensive player before coming to the Braves, and after seeing him every day at Turner Field for a large portion of the summer, I'm inclined to agree with this assessment. He's got good range, and a strong enough arm for the keystone, after coming up as a shortstop and getting some playing time at third base as well.
For the most part I was impressed with his double-play turning abilities with Andrelton Simmons too.
When looking at the advanced defensive metrics — take them with a grain of salt obviously, as it's just one year's worth of data — both UZR and DRS puts Peterson right in the middle of the league's qualified secondbaseman. His 2.1 UZR/150 is good for ninth out of the 18 players, and his -1 is good for 12th.
On The Bases
This is probably the most disappointing aspect of Peterson's game this season, in my opinion. After stealing 156 bases through four years in the minors (at a 78 percent success rate) Peterson was just 12-for-20 during 2015 — a dreadful 60 percent success rate.
The quantity of the stolen bases here isn't so much the issue as is the success rate. Anything between 75-80 percent is considered good and over 80 percent is extremely good. While Peterson doesn't have blazing speed by any means (Fangraphs lists him as a 50/50+) he is quick and his track record in the minors shows that he has the potential to steal bases effectively at the big league level.
All told, I think Peterson's season was about what one could have expected of the 23-year-old Louisiana* native. Peterson was never an elite prospect coming up with the Padres farm system, and while his May/June stretch was enough to get some people excited, I would be surprised if he ever regularly posted a BABIP in the .320 range.
Fortunately, Peterson showcased some good plate discipline at times throughout the season — he walked 9.4 percent of the time and saw 3.97 pitches per plate appearance — and has the potential to be an average hitter with gap-power if he can cut down on some swing-and-miss tendencies, refrain from expanding the strike zone and figure out left-handers.
There's clearly work that needs to be done to get the most out of Jace Peterson moving forward, but at the very least he's shown that he can play a solid-to-good second base while getting on base at a league-average rate. There is certainly some value in that, especially when you take into account his ability to play third and conceivably short in a pinch.
Steamer is projecting an almost identical triple slash from Peterson next season (.241/.312/.334), but I wouldn't be surprised at all to see him take a step forward, bump up the average a bit and cut down on the strikeouts. Peterson is never going to hit for much power, so his offensive value is going to come from his ability to take walks at a solid rate and use a line-drive approach to spray balls into the gaps.