Corey Seager is Finally Heating Up

As if the Dodgers weren’t already rolling along with the NL’s best record (43-19) and top offense (116 wRC+), over the past couple of weeks Corey Seager has begun rounding into form. The 25-year-old shortstop had started the 2019 season slowly after returning from a lost year in which he played just 26 games before undergoing both Tommy John surgery in May and an additional surgery to repair a torn left hip labrum in August. Over his past 12 starts, he’s collected 11 extra-base hits and the Dodgers have gone 10-2.

In case the injuries have clouded your memory, it’s worth recalling that Seager hit a combined .302/.370/.497 (132 wRC+) while averaging 24 homers and 7.8 UZR in 2016-17, leading all shortstops in WAR in both seasons, with 7.0 during his NL Rookie of the Year-winning campaign and 5.9 in his follow-up. He was an All-Star in both seasons, and finished a solid third in the NL MVP voting in 2016. In our 2018 preseason staff poll, he tied with Nolan Arenado as the third-most popular NL MVP pick behind Bryce Harper and Kris Bryant (only one staffer out of 40 picked Christian Yelich).

At least to this scribe’s reckoning, that optimism was based on the notion that the elbow soreness that had limited Seager to pinch-hitting duty for nearly two weeks in August and September 2017 was a thing of the past. But while the shortstop spent the winter working on strengthening the elbow, that proved not to be the case. He exacerbated his elbow problems with some questionable relay throws, his power never materialized, and he hit just .267/.348/.396 with two homers before being sidelined in late April.

The Dodgers took Seager’s rehab slowly; though he DHed in minor league exhibitions starting on March 4, he didn’t make his Cactus League debut until March 21, one week before the regular season opened. He homered off Cole Hamels that day, and when he homered again off Zack Greinke on Opening Day, all seemed right with the world. It was not, at least when it came to his performance. He homered just once over his next 39 games; through May 11, he was hitting a meager .225/.325/.341 (83 wRC+), his 0.6 WAR almost entirely a function of his defense and baserunning.

That arbitrary point — chosen simply because on May 12, Seager hit a grand slam off Nationals reliever Kyle Barraclough, the start of a more Seager-like stretch — came a week after Dodgers manager Dave Roberts described his slumping shortstop as “mechanics driven” and suggested that it was simply a matter of repetitions to recover his form, a perfectly reasonable explanation. From the Orange County Register’s Bill Plunkett:

“You’re taking at-bats in spring training but there’s a different intensity. And with Corey, his body, the levers, the hips, the elbow — everything has changed with surgery. So now you’ve got the body composition, the timing, the mechanics all of that stuff — you look at the player and you just expect him to roll out big numbers. But it’s just not that easy.”

…[Roberts] said he would have predicted 100 to 150 plate appearances would be required before Seager felt like himself again at the plate.

While Seager refused to blame his surgeries, he told Plunkett “that there were parts of his game-day routine that he had forgotten because he had been out for so long.”

Seager entered that aforementioned May 12 game with 160 PA; since then, he’s hit .304/.371/.633 with seven homers in 89 PA. Since May 24, the start of the even hotter stretch I cited in the first paragraph, he’s hit .333/.418/.729 with five homers.

What’s interesting about his turnaround is that this doesn’t appear to be a simple matter of his suddenly becoming more selective, or hitting the ball harder, or in the air more often. It’s true that relative to that particular point in time (which I have another reason for sticking with, detailed below), he’s swinging a bit more often, particularly at pitches outside the zone, and he’s making more contact on those pitches:

The thing is that within the more productive period (in which the sample size is admittedly smaller), he’s actually hitting more groundballs, not fewer, and his average exit velocity is only a smidge higher. That said, he’s pulling the ball more often, and the fly balls that he does hit are going further. Much, much further:

In that first period, just 8.2% of Seager’s fly balls (four out of 49) were hit to his pull side, compared to 59.2% (29 out of 49) to his opposite side (and thus 32.6% to the center); he slugged just .292 on all fly balls during that stretch. Since then, 17.9% of his fly balls (five out of 28) were pulled, 32.1% (nine out of 28) were to his opposite side, and 50.0% to center; his slugging percentage on fly balls skyrocketed to 1.333. On a per plate appearance basis, he went from pulling a fly ball once in every 40 PA to once in every 13.8 PA. If you’re wondering how all of this compares to vintage Seager (2016-17), he had a pull rate of 14.9% on his fly balls, and a .968 slugging percentage on them, so yes, this latest stretch is closer to his norm.

This airborne potency has been offset somewhat by Seager’s higher groundball rate, and pull percentage on those grounders, which has played into the shifts against him. Where he was hitting .324 with an 83 wRC+ on groundballs — of which 44.1% were pulled — through May 11, he’s at .241 with a 37 wRC+ and a 72.4% pull rate since. The latter set of results is a near-ringer for his 2016-17 baseline (.249 average, 37 wRC+) albeit with just a 52.5% pull rate.

Using Statcast and some very rough work in Photoshop that wouldn’t have flown during my previous career as a graphic designer, I’ve overlaid the graphs of Seager’s rolling exit velocity and launch angle (both using 25 batted ball increments, which for Seager covers about nine games), which required some stretching and scaling in order to match up the axes and averages:

Eh, it’ll do. As it turns out, the nadir of his rolling average exit velo by this method, on his 106th batted ball, landed in mid-game on May 12, just before the grand slam. He was actually very close to his peak average launch angle at that same point, and consistently rolling in the 15-20 degree range, compared to averages of 10.2 degrees in 2016 and 11.1 degrees in ’17. Again, this suggests that simply hitting the ball in the air with frequency wasn’t enough for Seager to be productive.

Here’s a look at his rolling groundball/fly ball ratio as well as his wRC+. A nine-game rolling average makes for a very noisy picture as does using both groundball and fly ball rates (which basically mirror each other), so I went with the ratio and 18 games, a span over which he averages about 50 batted balls (2.77 per game). Note that as the season has progressed, he’s become more productive even while hitting more grounders. All of which underscores the notion that for Seager, it’s a matter of producing higher quality fly balls rather than simply a higher quantity of them.

So does that mean he’s back? These are positive signs, to be sure. It’s worth noting while the shape of his production against righties has varied over the past three seasons in terms of OBP and SLG, its overall level has remained in the 120-130 wRC+ range, but his production against lefties has wavered. Even if we overlook 2018 due to his injury issues, the fact that he’s hitting just .221/.330/.299 (79 wRC+) in 91 PA against lefties this year, compared to .325/.389/.527 (144 wRC+) in 190 PA in 2017 suggests he’s not entirely in peak form, even if he’s been trending in the right direction lately. Monday’s home run off the Diamondbacks’ Robbie Ray was his first against a lefty since April 10, 2018 (Sean Manaea):

In a lineup that on many days can offer an above-average hitter at eight different positions, the fact that Seager hasn’t hit like an All-Star hasn’t been a problem. Nonetheless, given his place among the game’s top young stars prior to his injuries, it’s very encouraging to see him looking more like his old self.