Explaining Didi Gregorius’ struggles with the Yankees in 2019

After an offseason Tommy John surgery, the Yankees are happy to have Didi Gregorius back in the lineup, contributing to a team that’s been saddled with one injury after another all season long. He’s making all the plays the Yankees have come to expect from him at shortstop, but his offense hasn’t reached the same level as previous seasons, particularly his 2018 season in which he posted a sparkling 122 wRC+. The Yankees rely on Gregorius to serve as a potent left-handed bat, and his current 89 wRC+ suggests that he’s been a below average offensive player.

A quick glance at Gregorius’ batted ball metrics won’t raise too much concern. The shortstop’s average exit velocity is at a career-high 88 mph, and his barrel percentage is a career-high 6.1%. The veteran infielder is clearly still capable of hitting the ball hard and squaring up pitches, and his HR/FB rate, which is on par with last season, will support that claim. So why does Gregorius own a wRC+ 33 points lower than last season?

Much of Gregorius’ success at the plate the past two seasons stemmed from his ability to both produce great results against right-handed pitchers and hold his own against left-handers. Over the past four seasons combined, Gregorius posted a 95 wRC+ against left-handed pitchers and a 107 wRC+ against right-handers. Last season, his best offensive season as a pro, he put up a 127 wRC+ against righties and an above-MLB-average 108 wRC+ against lefties. This year he’s scuffled his way to a concerning 54 wRC+ against southpaws in 68 games of action.

To understand why Gregorius is struggling so mightily against left-handers, look no further than his diminished plate discipline. Last season he worked walks at a career-high 8.4% rate, compared to only 4.2% in his limited action this season. His swing percentages by zone against lefties the past two seasons paints a clear picture of his diminished plate discipline in 2019.

Baseball Savant

Baseball Savant

Gregorius is chasing 62% of pitches low and in from left-handers this season, compared to just 29% last season. Even throughout his stellar 2018 season, Gregorius did not record a single hit on a pitch down and in from a lefty.

Baseball Savant

Instead, he did all of his damage against southpaws when they left the ball up or out over the plate.

In 2019, Gregorius owns nearly identical strikeout and walk rates against both lefties and righties, but his batted balls tell an entirely different story. When Gregorius thrived against lefties last season, he sprayed 25.8% of batted balls the other way. This season he’s only hitting 14.3% of batted balls against lefties to the opposite field, and he’s pulling the ball at a much higher rate.

It’s easy to blame the short porch of Yankee Stadium for luring Gregorius in, but his pull percentage against left-handed pitchers is actually twice as high on the road than it is at home. Regardless, his .182 batting average against lefties could give Aaron Boone trepidation as he fills out his postseason lineup card against a left-handed starter, especially considering the flexibility afforded by the presence of DJ LeMahieu and Gio Urshela.

Keep in mind, Gregorius only has 70 plate appearances against left-handers this season, so the small sample size can magnify some of his struggles. It’s not unprecedented for a player to struggle with their approach after missing all of spring training and the first two months of the MLB season, but the playoffs wait for no one. The Yankees will be hoping Gregorius can fine tune his approach against left-handed pitching before the games truly start to count in a few short weeks.