What Happened to Didi?
This past Thursday the Phillies announced that they were parting ways with shortstop and 11-year MLB veteran Didi Gregorius by giving him his outright release. The move wasn’t much of a surprise as Didi wasn’t playing particularly well, and with Jean Segura set to return from the IL, and with 2019 first-round pick Bryson Stott ready to move to shortstop full time, Didi was clearly the odd man out.
The move may not have been a surprise, but it was newsworthy. Admittedly, writing “Didi wasn’t playing particularly well” is a bit of a sugarcoat, as he was downright abysmal in 2022, ranking dead last in bWAR among shortstops with -0.5 and second to last in OPS+ with 59. That level of performance and the subsequent release of a 32-year-old player who not that long ago was one of the better shortstops in baseball*was eyebrow-raising. It certainly had many people asking “What happened to Didi?”
(*Carlos Correa and Francisco Lindor were the only shortstops with more bWAR and a higher OPS+ than Gregorius over the 2017 and 2018 seasons.)
The answer is nothing happened to Didi other than he became a victim of a torrid, but relatively short hot streak, and of fans’ (and dare I say MLB executives’) high expectations and misevaluations based on that streak.
The reality is that Didi had a rather long stretch – 555 games to be exact – in which he was a serviceable, but not a particularly good player. Then midway through the 2017 season, he turned into Cal Ripken for a 98-game stretch that carried over into April of 2018. Yet before the calendar turned to May in 2018, the real Didi returned for 416 more career games of below-average performance.
You may think there has to be more to it, and we’ll return to that in a minute, but let’s look at the clear lines of demarcation in Didi’s performance over his career. (*Author’s note: With the exception of 2015 when Didi played superb defense, his glove work and base running were more or less consistent over his career, so for the purposes of brevity we’ll stick to his offensive swings in production today.)
From the time Didi started to get regular playing time in 2013, through July 15th, 2017 Gregorius had 2,148 plate appearances and posted an unimpressive 93 wRC+. Then from that point through April 28th of 2018 (not counting his great ’17 postseason), he turned into Roger Maris if Maris could play shortstop. That 98-game stretch saw Didi post a 144 wRC+, .575 SLG with 25 long balls, and 79 RBI – all of which led MLB shortstops over that span.
Then when the clock struck midnight on April 28th, 2018, Didi lost his glass slipper and never got it back. Over the remaining 416 games and 1,677 PAs of his career, he’d put up a wRC+ of 88 – similar to the hitter he had been prior to July of 2017. Again, not terrible, but far more than a pitching wedge into the short porch away from good.
You may be thinking that the date of the start of his hot streak seems random, and perhaps Gregorius made an adjustment or philosophical change at the start of the 2017 season. His pull percentage in 2017 was a career-high and it did in fact continue to increase for four consecutive seasons after that. That may lead us to think that increasing pull rates in Yankee Stadium is what led to the increase in production. But that doesn’t explain why he held an essentially league average 102 wRC+ more than halfway through 2017, then immediately became an obliterator of baseballs with a 144 wRC+ over his next 98 games. It also doesn’t explain why his production continued to drop over the last several years of his career even as his pull rates stayed elevated.
Of course, you’re probably wondering when I’m going to acknowledge the elephant in the room that is Didi’s elbow injury and subsequent Tommy John surgery. Although one can never say an injury of that degree would have zero effect on a player, in this case, it had little to no effect. Didi injured his elbow in Game 2 of the ALDS in 2018 against Boston, and the regression to his personal mean began far before that. His 98 wRC+ over the previous five months was a big drop from his 144 wRC+ in the three baseball months prior.
Perhaps pitchers and defenses adjusted to him? In the case of pitchers no, as Baseball Savant shows no significant changes in how he was pitched to. Defenses did begin to shift against him more often after 2018, but his performance against shifted defenses varied both before and after 2018, so there was little effect on his long-term numbers, if any.
What was consistent throughout Gregorius’ career is that comparatively speaking, he never hit the ball particularly hard. In the eight seasons in which Statcast has tracked such matters, Didi finished below the 10th percentile in average exit velocity six times. In his two best seasons in this regard, he finished in the 17th and 28th percentile, so even at his best he wasn’t exactly worrying opposing fielders. (Unsurprisingly, his hot streak from July of ’17 through April of ’18 did have a 31-point bump in Batting Average on Balls in Play from the first half of 2017.) As you’re a reader of Off the Bench, you’re surely aware that if a batter doesn’t strike the baseball hard, it’s virtually impossible to sustain success for any substantive period of time.
To me, “What happened to Didi?” isn’t the correct question. “Which is the real Didi: The guy with close to 4,000 plate appearances of below-average hitting, or the guy who was productive over a 98-game stretch?” is the better question. The answer is that Didi was a serviceable but not impactful player who had a brief run that fooled folks in baseball into believing he was better than he was.
To be clear, this isn’t a knock on Didi. Baseball is very, very, hard, and the percentage of MLB players who can do it on a great level over the course of an entire career is infinitesimal. If this is indeed the end of Gregorius’ career, he can walk away knowing he had a very good one. Yet he is still a cautionary tale for the rest of us to beware of small sample sizes, and in baseball terms, 98 games is not a big one.
