It isn't quite the Jesus Montero for Michael Pineda swap, but trading Shane Greene for Didi Gregorius has received a fair bit of coverage in the early part of the season. More so in April, when a strong start to the year by Greene loomed over a slumping Gregorius, leading to suggestions that the Yankees may have lost the trade. Judgements were of course premature then, and they are still premature now even if Greene has been sent down to the minors as Gregorius remains in the Bronx. The likelihood is that Greene will return to Detroit sooner than later. The Yankees gave up a talented young pitcher, albeit with an uncertain future, to obtain Didi. This hasn't changed and it remains a steep price, for the move to work out in the long run Gregorius needs to solidify his hold on a starting shortstop position.
As the season has gone on, Gregorius has appeared to settle into the role defensively. After a shaky April, the highlight reel plays have returned in May and June. While he doesn't appear to have gotten over the occasional lapse, his range and strong throwing arm have established himself as an asset to the run-prevention element of the team. For Gregorius to remain a starter in the long-term though, he needs to be able to hold his own offensively as well. Helpfully, he is showing signs of improvement at the plate.
There are a couple of qualifiers to this. Firstly, we're about three-eighths of the way through the season, when there is some substance to 2015 data-points but where it remains early to be drawing extremely meaningful trends about in-season changes. Secondly, Didi was so awful in the first quarter of the year that there really was nowhere to go but up. However, while it is always worth noting when we're looking at trends in smallish samples, it doesn't always mean we have to dismiss those trends altogether. A mid-May cut-off, while reasonably arbitrary, does represent a pretty significant divider in Gregorius' first season as a Yankee. Up until the 15th of May, Didi was simply awful in his 115 plate appearances; .202/.263/.231, .228 wOBA, 38 wRC+. Since then, 70 plate appearances of just over league average performance; .281/.329/.422; .328 wOBA, 109 wRC+. The first split was simply not good enough for a major league ballplayer; the second represents a credible offensive threat at a premium position.
A reasonable hope for the Yankees might well be that Gregorius is player somewhere between the extremes, a below average offensive player but not a hole in the lineup. Perhaps somewhere around his career 80 wRC+. Good enough to where he can continue to be run out there every day while he remains an asset defensively. If we're looking for something to be optimistic about, though, there might be something to monitor in his hitting distribution. His batted-ball splits haven't changed much, at all, nearly half his batted balls are going as grounders and have been all year. The all-important line-drive rate has actually fallen slightly, now a bit under a fifth or so. What is more interesting is to see where those balls have been going.
It's not the clearest shift, but it's a significant distribution to use more of the field, particularly going the other way. Perhaps it's just the way the hits have gone, perhaps a change in approach, or perhaps just a small sample size. Whatever it is, it's helped. Even if his line-drive rate has fallen, he has gotten nearly twice as many hits in the last month from line drives; from five before mid-May to nine since. Crucially, more than half of those nine line-drive hits have gone to left or center field. Gregorius only had one such hit before mid-May.
His power, what power he has anyway, continues to be pull power. Scattering a home run among a few doubles to right field has helped boost his ISO from an appalling .029 to a much more palatable .141 since the 16th of May. For Gregorius to continue contributing offensively, the threat of extra-base hits will hopefully remain to right field, but he will need to continue using all fields to get on-base with any reasonable regularity. If it is a change in approach that is driving the change in his hit distribution, it will hopefully help boost his ceiling to one where he might remain at least close to an average hitter.
It might well be interesting to see what these heat maps tell us at the end of this season, and if there truly has been a significant shift in how Gregorius performs at the plate. Perhaps then we might get a better handle on how this trade has panned out for the Yankees. If the Montero-Pineda swap is any guide though, even one year out will be too early for final judgements.