Andrelton Simmons will be a starting shortstop in the big leagues for a long time because of his glove. He's probably the best defensive player in the world and will likely continue to be for at least the next few years. It's tough to really state just how important Simmons is to the Braves on defense.
At the plate, though, is an entirely different story. He's been atrocious this season.
Simmons posted a solid line of .289/.335/.416 as a rookie in 2012. With a .310 BABIP, reasonable walk rate and low strikeout rate, anything close to that over a full season would make him one of the best shortstops in MLB.
His sophomore campaign wasn't quite as good. He batted .248 with a sub-300 on-base percentage, but 17 home runs and a near 1-to-1 walk-to-strikeout ratio was good enough to post a 91 wRC+ and .692 OPS, which was tolerable because of his glove.
Through 131 games this season, Simmons is hitting .238 with a .608 OPS and 69 wRC+.
Only Jean Segura and Zack Cozart have worse numbers among qualified shortstops.
B.J. Upton's OPS is .611. His wRC+ is 71.
In other words, B.J. Upton has been a better hitter than Andrelton Simmons in 2014.
Andrelton's strikeout rate (10.9%) is the worst of his career, as is his walk rate (5.9%). He has just seven homers on the season, and he's hit just two since mid-June. His ISO has dropped to a petty .090. He also continues to not be a threat on the base paths, though to be fair no one ever expected him to run much.
Simmons will continue to be one of the game's top shortstops because of his glove alone, but this season at the plate has been a nightmare. You could say it's been a nightmare for the entire lineup, really.
If Simmons is going to post a ~.600 OPS moving forward, the Braves have a serious problem because they don't have enough at the other positions to make up for the shortstop's shortcomings.
A team can withstand one (or maybe even two) bats like Andrelton's at the bottom of the order, but they better have a damn good 1-6. The Braves don't have that, and it's a big reason why finishing above .500 this year will prove to be a challenge.