Is Didi Gregorius for Real?

Playing shortstop is a young man’s game. The list of top-tier shortstops age 25 and under in the game right now is so extensive that it’s impossible to pare down to a quick three- or four-name list without leaving off a potential future MVP. If you’re interested in fawning over those names and debating who among them is the most valuable, I’d recommend keeping an eye on Dave Cameron’s trade-value series this week. But right now, I want to talk about a guy who suddenly looks like a grizzled veteran next to the new wave of shortstop talent: 26-year-old Didi Gregorius.

Over the past month, Gregorius has been the most productive shortstop at the plate. Go back a bit further and you’ll find that, after struggling in the first month of the season, he’s posted an impressive 131 wRC+ since May 8th. On the season as a whole, though, his 109 wRC+ ranks a respectable, if uninspiring, 11th among shortstops behind eight (!) members of that 25-and-under age bracket. There’s no argument to be made that Gregorius is anything like the best shortstop in the game right now, but he is in the midst both of a remarkable stretch and also his finest overall season at the plate. He also has three more years of team control remaining, which makes it worth investigating to what extent this Gregorius breakout is for real.

The most obvious and, perhaps, the most fun part of Gregorius’ breakout has been his power surge. He’s recorded five home runs in his last 11 games, which has helped boost his ISO to a career high .169. He’s hardly the only shortstop to grow into power after a few seasons in the majors: Brandon Crawford and Zack Cozart followed a similar trajectory. Gregorius’ power is aided by the fact that he’s a left-handed hitter who gets to play half his games in Yankee Stadium. Unsurprisingly, his home/road power split is rather stark:.210 ISO at home, .132 on the road. If I were a team interested in acquiring Gregorius, this would be a concern, but unless the Yankees are planning to move anytime soon, they should feel comfortable accepting that Gregorius possesses the ability to make the most of his home ball park.

There is something about Gergorius’ newfound power, however, which necessitates pouring a bit of cold water on the idea that he’s tapped into a new ability which will help elevate him to a new level. Check out his season-by-season ISO:

Yes, Gregorius is hitting for more power and that’s a great thing, but he’s not alone. Power is up across the league and, rather than pulling ahead of the pack, Gregorius is merely keeping pace with league average. (Gregorius recorded only 21 plate appearances in that 2012 season, so the relevant start date for his ISO comparisons begins in 2013.) The power increase among shortstops is even more stark than the league-wide trend. Since 2014, the average ISO for shortstops across the league has risen from .113 to .151 — nearly forty points! So, yes, the new power is fun to watch, but it’s not going to alter substantially Gregorius’ standing in the league.

However, there is something else on which Gregorius has improved at the plate in recent seasons which is a bit more encouraging.

As power has risen across the league, so too have strikeout rates. Gregorius, though, has seen his strikeouts plummet this season. Out of 147 qualified hitters this season, Gregorius ranks ninth in strikeout rate at 11.0% — a significant drop from the career 15.9% strikeout rate with which he entered the season. The biggest key to his improved ability to avoid strikeouts has been a jump in contact rate.

After maintaining a steady contact rate around 79% through his first three seasons with extended major-league playing time, he’s brought that rate up to 85% this season. You can see the improvement on his heat map (2015 is on the left and this year is on the right):

His plate coverage on inside pitches has improved, but the biggest improvement has come on pitches down in the zone. The contact increase and strikeout decrease has helped Gregorius post a .298 batting average this season, which is well above his career mark of .262. Batting average as a standalone metric may not have much value these days, but I’m bringing it up because it’s the reason his on-base percentage has risen moderately (2016 – .327; career – .318). It’s the driving factor in that improvement because, unfortunately, the downside to Gregorius making increased contact is that he’s not working counts deep enough to draw free passes. As his strikeout rate has plummeted to a career low, so has his walk rate. Gregorius doesn’t only possess the ninth-best strikeout rate among qualified hitters, he also has the ninth-worst walk rate (3.5%). As a result, his gains in on-base skill this season have been middling.

Gregorius is not in an enviable position. Not only does he play in the shadow of that other former pinstriped shortstop, he also plays in the same division as one of those star-level 25-and-under shortstops,  Xander Bogaerts; a star-level 25-and-under sometimes-shortstop, Manny Machado; and one of the best shortstops over the past decade, Troy Tulowitzki. Nothing about what Gregorius is doing right now suggests that he’s an emerging star who will be able to stand out among an astonishing pool of young, talented players at the position. That’s not to say, however, that the improvements aren’t real. Contact is good. Power is good. Fusing an improvement in both areas is very good. Possessing a league-average bat at shortstop still gives a player very real value and Gregorius is putting himself in a strong position to provide that level of value going forward.