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Clayton Kershaw Has a Home Run Problem

The Dodgers ace is surrendering long balls at an alarming rate this season, and it may be due to the location of his once-dominant fastball

(AP Images/Ringer illustration)
(AP Images/Ringer illustration)

Mets infielder José Reyes entered Monday’s 10–6 loss to the Dodgers with the worst OPS of any qualified hitter in the National League. His slugging percentage lagged behind that of several Padres pitchers. And he was facing L.A. lefty Clayton Kershaw, against whom he had hit just 3-for-16 with no extra-base knocks in his career. Yet in his first at-bat, this happened:

A few innings later, he chased the Dodgers ace with another homer, his second of the night — and, more distressingly for the pitcher, Kershaw’s fourth allowed of the game (a career worst) and 17th allowed of the season (also a career worst, already, in mid-June). Only six pitchers have surrendered more homers this season than Kershaw, who — despite maintaining a top-five ERA, K%, and BB% in the NL — is exhibiting an unprecedented problem. In 263 starts before 2017, Kershaw had allowed three homers in a game just twice; in 15 starts this year, he’s already reached that mark three times.

Kershaw’s sudden proclivity for giving up the long ball is especially surprising as it acts as an antithesis to his career up to this point. From his first full season through the end of last year, no qualified starter had a stingier HR/9 rate, and even as the league’s home run tendencies increased in recent years, Kershaw remained a holdout, the tireless trout — no, not that one — swimming against the tide. But his typical HR/9 rate has tripled this season, and after Monday’s four-dinger outing, he’s now allowing homers at a worse-than-average rate for the first time in his career.

The easy, reflexive answer when confronted with such an ahistorical conundrum is that bad luck is the culprit, and one key indicator suggests that may be the case. Examining again the period from Kershaw’s first full season through last year, his 6.7 percent HR/FB mark was second-best among 245 qualified starters; this year, that rate — which even in decent-sized samples can veer outside a pitcher’s control — has ballooned such that 19.1 percent of his fly balls have passed over the fence, sandwiching him between noted homer-allowing aficionados Ricky Nolasco and Bronson Arroyo for the eighth-worst mark in the majors.

But a deeper look reveals that Kershaw’s run of pained, hands-on-knees crouches is not a mere product of random misfortune; rather, opposing hitters are hammering his pitches. Kershaw’s first 13 homers allowed this year traveled an average of 406 feet, per ESPN’s Home Run Tracker, and all of those homers came with an exit velocity of at least 100 mph; besides Jay Bruce’s fifth-inning laser on Monday night, all would have left a majority of MLB ballparks. (That unanimity compares him unfavorably to, say, Jake Arrieta, who has allowed 12 home runs this year, four of which would not have cleared the fence in almost any park without wind assistance.)

It’s not as if Kershaw has been surrendering homers only to renowned sluggers, either. The Mets’ Gavin Cecchini recorded his first career homer on Monday, after never reaching double-digit blasts in any minor league season, and the likes of Colorado outfielder Gerardo Parra and Cleveland catcher Roberto Pérez have gone yard against Kershaw, too.

There’s a larger problem at play here, and it seems to stem from Kershaw’s fastball location. Any pitcher, even Kershaw, can hang a curveball on occasion, but the Dodgers ace has been living dangerously with his four-seamer, his most frequent pitch, which is a bigger issue. He has already allowed 11 homers off his fastball this year, per Brooks Baseball’s pitch categorizations, after allowing just six against that pitch in all of 2016, and a quick look at the two seasons’ respective heat maps finds a pitch that has floated more regularly over the middle of the plate this year. On this strike-zone chart, darker colors correspond with more frequent pitch locations, and in 2016, Kershaw kept his four-seamer up and in against righties.

(Baseball Savant)
(Baseball Savant)

This year, though, his fastballs have been concentrated lower and closer to the middle of the zone, with more run toward right-handed batters’ outside half, where any professional hitter — particularly in this age of power — can crush an average-velocity mistake, like Mark Reynolds did with this 92 mph offering, or like Parra did with a near-identical pitch that same night at Coors Field back in April. On Monday, Reyes’s first homer came on a 93 mph four-seamer that leaked too far over the plate, allowing the batter to extend his arms and generate the requisite force to pull the ball over the fence. Kershaw’s home run pitches are almost all bunched in that same sweet spot.

(Baseball Savant)
(Baseball Savant)

We can look at Statcast data to explore this effect further. Over the past two seasons, opposing hitters “barreled” Kershaw’s fastball just 3.3 percent of the time when they made contact; this year, that rate has more than doubled, to 7.6 percent. That’s not to say that all of Kershaw’s fastballs are hittable now or that he should throw it less — it’s still an effective pitch on aggregate — but rather that he appears to be missing his spot more, and batters are taking greater advantage, than ever before.

He’s still the best pitcher in baseball, despite recent buzz for Max Scherzer (who, it’s worth noting here, allowed 27 and 31 homers in the past two seasons, respectively), but just as Kershaw solved one issue — that of a less-lively slider — another one has appeared, adding another layer of vulnerability to a previously pristine portfolio. The expectation is that he will tighten his control, snap the heater back into its rightful place near the strike zone’s corners, and return to his homer-defying ways, but after a night spent coughing up runs to Reyes and Cecchini, Kershaw’s homer troubles have matured from odd statistical blip to real, tangible concern.

That’s a strange sentiment about a pitcher with a 2.61 ERA and Kershaw’s track record, though it’s precisely because of that history that even a decline to league average in one area is cause for alarm. We don’t expect anything approximating average from Kershaw, just as we don’t expect anything approximating average from his position-player counterpart, Mike Trout. Over the years, Trout has fixed all the small imperfections that ailed his game — from struggles against high fastballs to a weak throwing arm to patience bordering on passivity early in the count — and now it’s time for his Los Angeles pitching complement to do the same. He’s Clayton Kershaw; he’ll almost certainly adjust. But the fact that he even has to is notable all on its own.