You may want to check your ballpark dimensions before signing Didi Gregorius.
In the right environment, Gregorius has the upside of a solid hitter and defender. We’ve seen that in his last two stops: In both New York and Philadelphia, Gregorius benefitted from disproportionally-helpful park factors that lifted his offense to better-than-expected levels and turned him from a solid, glove-first shortstop into a well-above-average impact player. Yankee Stadium and Citizens Bank Park each fit Gregorius’ offensive profile incredibly well.
Last offseason, Gregorius joined the Phillies on a one-year, prove-yourself contract. The sides agreed on a $14 million salary, as Gregorius was coming off of a poor offensive season following his recovery from Tommy John surgery. In 1,139 plate appearances in 2017 and 2018 combined, Gregorius posted a 115 wRC+. That output dipped to just an 83 wRC+ in his return-from-Tommy-John year, but ticked back up again in 2020. With the Phillies, Gregorius slashed .284/.339/.488 with 10 homers and a 116 wRC+ in 237 plate appearances, proving that, yes, the offense had only taken a breather in 2019. The defense — which has been about average throughout his career — was more of the same, and Gregorius was ultimately worth 1.4 WAR in 60 games.
Clearly, Gregorius’ upside is severely limited without the offense. While he is indeed a decent defender at shortstop, the glove alone does not carry his game. Rather, a combination of offense and defense is what has turned Gregorius from a 1.6 WAR/162 player early in his career to a 3.8 WAR/162 player since joining the Yankees in 2015.
It’s not as if Gregorius’ bat took some huge step forward midway through his career, however. Though Statcast data only goes back to 2015, unfortunately coinciding with his move from the Diamondbacks to the Yankees, Gregorius still hasn’t become a big-time basher in the years since. In 2017, for example, when Gregorius posted his first above-average offensive season, his average exit velocity ranked in the 6th percentile. He had the seventh-largest wOBA minus expected wOBA in the majors. It seemed as if luck was driving Gregorius’ offensive success, but was it really?
Gregorius followed up his solid 2017 campaign with an even better 2018 season, hitting 27 home runs and posting a 122 wRC+. The defense was good once again, and his 4.7 WAR made him the 28th-most valuable position player in baseball. Though improved year-over-year, the underlying numbers didn’t, in any way, pop (pun intended). Gregorius’ average exit velocity did jump from 84.5 to 87.0 mph — moving him from the 6th percentile to the 22nd percentile — but, once again, he was among the leaders in wOBA minus expected wOBA. The “luck” had carried over.
Jump ahead to 2020, and we find that the story is only more extreme. Gregorius’ average exit velocity puts him in the 4th percentile (!) and yet the offensive output was still markedly above-average:
There is a pretty clear relationship here between average exit velocity and wRC+, even in the small sample 2020 season. Gregorius is one of few who buck the trend, and it’s pretty clear why he’s been able to do this nearly every single year. Quite frankly, Gregorius is excellent at one extremely important skill: playing to his ballpark.
Starting in 2017, Gregorius started pulling the ball more often, and in each year since then, he’s only done so at higher rates. When combining this with his 43 percent fly ball rate in that stretch, Gregorius starts to build a profile that looks much more like that of a traditional power hitter, with a focus on pulled fly balls, than one of a seemingly light-hitting shortstop. Gregorius is not a power hitter by any means, but he’s angled his game in such a way to squeeze out every ounce of power that he has. It’s actually incredible. Just look at his career home run spray chart:
Gregorius is the perfect example of why park factors are just averages. Though park-adjusted statistics such as wRC+ do account for playing in more hitter-friendly stadiums such as Yankee Stadium and Citizens Bank Park, they base their adjustments in how the average hitter plays. Gregorius is an extreme case, and in a way, he almost breaks the park-adjusted offensive numbers. He has benefitted from playing in two of the six most-friendly ballparks for home runs from left-handed hitters. But who could blame him for taking full advantage of what those ballparks have to offer? In the Statcast Era, no player has hit more home runs at an exit velocity of no more than 95 mph than Gregorius. Bumping the threshold up a touch, Gregorius has hit nearly half (52 of 107!) of his home runs since 2015 with an exit velocity of no more than 100 mph, again leading the majors.
It’s hard to say what Gregorius’ offensive output would look like in a less-friendly ballpark, considering he’s only been playing in favorable environments in each of the last six seasons. However, since so much of his performance rests on his ability to golf balls into the right field seats, that likely is where teams will find the most value out of him. But it may also limit his suitors. The Angels, for example, may be a player for Gregorius this offseason, but could balk at the idea of having him play in a slightly below-average park for lefties. It’s hard to really know how Gregorius would play there, considering his numbers in road parks have been solid in prior years as well, but one would think that a less-friendly park would only hurt his offensive numbers overall.
The Reds would be a much more effective fit for the shortstop, considering Great American Ball Park is even more friendly to lefties than Citizens Bank Park. They’ve already been mentioned as a potential suitor, and I think the two sides would match up quite well. For Gregorius, the same approach would continue to allow him to slug. And for the Reds, they’d be loading the dice in favor of all-around shortstop production, in the range of 3 to 4 WAR. A marriage there just seems too good to be true.
With that said, I’ve only been making contract predictions, not team predictions. I’ll say Gregorius gets a three-year, $45 million deal, and the Angels, Phillies and Reds should all be among the teams in on him. But this is a message to whomever signs Gregorius: Make sure your ballpark can appropriately accommodate lefties. He’ll certainly appreciate the output that comes along with it.
Devan Fink is a sophomore at Dartmouth College and a Contributor at Beyond The Box Score. Previous work of his can be found at FanGraphs and his own personal blog, Cover Those Bases. You can follow him on Twitter @DevanFink.