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Clayton Kershaw’s Kryptonite in 2017 has been home runs

His four-seam fastball and its location are mostly to blame.

MLB: Washington Nationals at Los Angeles Dodgers Jayne Kamin-Oncea-USA TODAY Sports

Clayton Kershaw has been synonymous with dominance since breaking into the league in 2008. There hasn’t been a better pitcher by any measure since that time and every baseball fan knows it.

So it will likely come as a shock when I say it may be time to start worrying about Kershaw. I say this because it appears he has a significant issue in the home run department, as he’s given up 17 home runs in just 12 starts this season. That sounds like a lot for even the average top-of-the-rotation starter; it’s that much more for someone of Kershaw’s caliber, who is several levels above average.

Typically, we wouldn’t be worried about Clayton three months into a season, given his track record, but this home run issue seems to be getting progressively worse as we move deeper into the season. He’s now surrendered a home run in a game for five straight starts — the first time he’s done that in his career. His next highest streak of home runs allowed was four straight starts, which hasn’t happened since 2011, and before that, 2008. His most recent start against the Mets on Monday was also the first time in his career that he has ever allowed four home runs in a single start.

Over the past five games he’s allowed a total of 10 home runs, which is more than he allowed in all 21 of his starts last season. In fact, Kershaw, through 15 starts and 103 13 innings this season, has already set a career high in home runs allowed. This struggle has definitely frustrated Kershaw.

Despite the massive uptick in home runs, everything else is just about as expected with Kershaw: His strikeout and walk rates are right in-line with what he’s averaged over the past several seasons, and his run prevention and field independent numbers are as well (if you set aside the home runs). Additionally, he’s still among the league leaders in each of those categories. The fact that every other statistic is perfectly normal makes his home run problem all the more intriguing.

There was an article earlier this month by Jeff Sullivan of FanGraphs, which noted that Kershaw was still experimenting with his release point on certain pitches. However only one of the home runs he’s allowed came off a pitch that deviated from his normal release point threshold. The pitch was a two-seam fastball to Jay Bruce.

Baseball Savant

The majority of the 17 home runs have come off of his fastball, 11 in total (ten off of his four-seam fastball and the one off of his two-seamer that I mentioned earlier). Putting the two-seamer aside, it appears the home runs off of his fastball have been caused by a change in pitch location on his four-seamer. As you can see in the charts below, in 2015 and 2016, Kershaw primarily located the pitch on the edge, away from right handed hitters. This season the four-seamer location has moved slightly down and further toward the center of the plate, causing a large percentage of those pitches to run down the heart of the plate.

Baseball Savant

Batters are sitting on Kershaw’s fastball since it’s his most-used pitch, with a career average close to 62 percent. Although his four-seam usage has dropped to just under 46 percent percent this season, when batters are sitting on it and you’re now throwing it closer to the center of the plate than you have before, it’s not surprising to see so many home runs result. It doesn’t matter how good of a pitcher you are; if your fastball is being consistently located right down the middle or just slightly off center, you’re going to get burned.

I created the overlay below using Baseball Savant’s Heatmap and Pitch Charts, and it indicates exactly that. Hitters know Kershaw is throwing the fastball closer to the middle of the plate so they’ve adjusted and are looking for it. Further evidence that hitters are sitting on the fastball: seven of the ten home runs that came off his four-seam fastball have come in 0-0, 1-0, or 1-1 counts.

Baseball Savant

These home runs are beginning to weigh heavy on Kershaw’s starts. Kershaw has pitched at least seven innings in all his starts, except when he’s allowed multiple home runs — which has happened in a whopping four of his 15 starts this season. And the only two times the Dodgers lost one of his 15 starts came in games when Kershaw allowed multiple home runs.

The issue with home runs isn’t just historically bad for Kershaw compared to anything he’s done before; he’s also among the worst in baseball this year in home run prevention. He’s currently tied for 8th in total home runs allowed and 8th in home runs per flyball.

As we loom closer to the All-Star break, the time is ticking for Kershaw to work out this issue so he can get back to prime form for the Dodgers down the stretch and into the postseason. He needs to bring his fastball back toward the edge of the plate so that batters are not barreling it up as easily. Teams are starting to figure out that Kershaw’s location on his four-seam has adjusted and they are adjusting themselves to hit it. If Kershaw can’t get the fastball back to the location it needs to be, his home runs may become a liability that eventually costs him and the Dodgers more than just a couple of regular season losses.

Ron Wolschleger is a Contributing Writer for Beyond the Box Score as well as Bless You Boys. You can follow him on Twitter at @FIPmyWHIP.