By the numbers (fangraphs’ Def rating), Simmons’ defense was the second most valuable in 2013, trailing only Manny Machado, with ratings of 31.6 and 33.6 respectively. Shortstop Mark Belanger’s 1975 season was rated as the best single season ever by the same metric, while Simmons’ 2013 season ranks 54th best. At just 24 years old, I think it’s safe to say that Andrelton is an up-and-coming star in the MLB, based on his glove alone.
We can assume that his glove will continue to be a valuable asset for the foreseeable future. Nobody in their right mind will disagree with that. With just over 200 games of MLB experience, Simmons has collected 6.9 WAR. With a 94 wRC+, his bat is a tick below average. With youth on his side, surely there is room for improvement. How much offense can he provide?
Simmons presents an interesting case. On the surface, his brief playing time in 2012 was similar to his 2013 year. In 2012, he posted a slash line of .289/.335/.416, with a .310 BABIP, three homers, a mid 6% walk rate, and a K% of 11.5%. In 2013, he improved his strikeout rate while keeping a stable walk rate, added some home run power, but his overall numbers suffered. His suppressed slash line of .248/.296/.396 was largely due to a .247 BABIP, which would lead one to believe that he is set to bounce back and build on his 4.7 WAR from 2013. Steamer sees his bat progressing in such a way, as the projection system has his slash line at .267/.318/.408, good for a 102 wRC+.
His offensive profile is extremely dependent on BABIP. If it cranks back up to the .300 range, his overall numbers will be fine. If his BABIP slumps in the mid .200’s like it did last year, you’re looking at a .300 OBP. In looking at his batted ball profile, it is clear that his drop in BABIP last year was due in part to an overall shift in his approach. In 2012, he had a GB/FB ratio of 2.05, which was nearly cut in half in 2013 to 1.08. He has proven that he knows how to hit an infield fly like nobody else, as his 17.7% IFFB% led the league in 2013, and has been steady throughout his MLB career. Everything in his batted ball profile, other than the GB/FB ratio, has remained steady.
To pull a quote straight from the fangraphs glossary, “players that don’t hit many balls in the air (higher GB% with lower FB% and LD%) generally have higher BABIPs and batting averages, but have limited power.”  This makes intuitive sense, as more balls will find holes than fly balls would drop in for hits. And as Mike Podhorzer notes, Simmons made the trade of speed for power.  While I enjoy and agree with the premise of his article, it’s also worth noting that he more likely traded OBP for SLG.
Simmons is in a weird middle-ground of a guy that should be rifling off grounders to get on base, and one who should try to hit it as far as he can every time up. To generalize even further, he went from an Ichiro-type batted ball profile in 2012 (grounders = high BABIP) to Jose Bautista in 2013 (flyballs = low BABIP with power). The problem is that he doesn’t have the speed of Ichiro, or the power of Bautista. If Simmons can keep his batted ball profile of 2013 while also raising his BABIP, then that would clearly be an optimal situation as his overall numbers would rise. Alternatively, and in my opinion the more likely scenario, is that his BABIP will remain suppressed so long as he continues to hit the majority of his contact softly in the air.
All we can do is wait to see which profile Simmons will grow into. The issue isn’t with his ability to make contact, but rather making solid contact. If he can’t improve his line drive ability and cut back on the infield flies, then I would suggest that he should start peppering the infield with grounders in order to raise his BABIP; this would presumably result in a slash line similar to what he posted in his rookie campaign of 2012. If he can indeed start to drive the ball and tap into some power that we have yet to see, then we are dealing with someone with immense potential.
Frankly, as it stands right now, I don't think Simmons has it in him to be the power hitter he tried to be last year. His 2012 production seems entirely legitimate, and could be sustainable going forward (as could his 2013 numbers). There is nothing wrong with a league-average bat with elite defence, as evidenced by his 2.2 WAR in roughly a third of a year in 2012. Prorate his rookie numbers over a full year, and you're looking at a very special talent. He doesn't need to hit 17 home runs again, or anything close to it. He just needs to focus on getting on base, and letting the power come to him.
How much of his 2013 shift in batted ball profile was a result of him, rather than a team-wide shift in philosophy as well as him leading off once in a while, I don't know. In the meantime, I’m going to enjoy watching Simmons produce at an all-star level, regardless of how his bat develops or what type of contact he chooses to make. Just be on the lookout if he starts to drive the ball with authority, as that could vault him into becoming one of the best in the game.
Thanks for reading!