Clayton Kershaw is Allowing Home Runs at an Alarmingly Normal Rate

Header photo by John McCoy

Few pitchers in the history of the game have come even close to what Clayton Kershaw has been able to do so far in his career. He’s not even 30 years old yet, and he’s won 3 Cy Young awards, an MVP, and 4 ERA and WHIP crowns. His 2.36 career ERA leads all active pitchers and had he been healthy enough to pitch even 15 more innings last season, he would have shattered the record for single-season strikeout to walk ratio, an incredible 15.64. He walked 11 batters in 149 innings last season, an unbelievable .7 BB/9 that would have been a top-5 mark all-time among pitchers past 1900 (even though most batters still called their own balls and strikes back then).

He’s led the league in WHIP more times (5) in 11 seasons than Sandy Koufax did in 11 or Greg Maddux did in 22. He leads the NL so far this season, well on his way to his 6th season leading the league that would tie him 2nd all time with Pedro Martinez, Carl Hubbell, and Walter Johnson. That’s fine.

Excluding his phenomenal 2016 season, which ultimately doesn’t count because of the innings qualification, he is on pace for a career high strikeout/walk ratio and walks per nine, so his command is still terrifyingly precise, but he is allowing home runs at an alarming rate. Well, alarming for Kershaw standards. Through 9 starts and 62.2 innings, he is just under a quarter of the way to his career average in games started and innings pitched. If we were to multiply his home run totals by 3.66 (because 3.66 times 62.2 innings = 227 innings, his 162 game average), we get 25.

25 is not a bad total, but by Kershaw standards it is pretty bad, a career worst by nearly double. Given his extreme ability to locate most of his pitches (spoiler alert, keep reading), Kershaw might allow more home runs than walks this season. That is neither here nor there, but we’re entering uncharted Kershaw waters so far this year. His command is still the cream of the crop, but at the same time, when he misses with his pitches, hitters are punishing him for it. He’s throwing his fastball 47.9% of his pitches this season, the lowest in his career and a number that has decreased every season since he debuted in 2009 at 71%. Meanwhile he is throwing his slider at the highest rate of his career, 36.9%, but is also throwing it the hardest he ever has at an average of 89.1 miles per hour.

The above photo is Kershaw’s slider placement in 2016. In his career, Kershaw’s opponent batting average against his slider is a measly .161, in large part because he does such an amazing job making the pitch dive in on a right-handed batter, forcing him to either drill it weakly into the ground breaking their bat, missing it entirely, or, rarely, flipping it over the head of the third baseman. It is equally difficult for left-handers, watching a pitch that looks like its going to kneecap you and then ends up called for a strike on the outside corner. In short, Kershaw managed to bury his slider so far against the black and sneak it just above the bottom of the zone that hardly any hitter can be successful against it.

2017 is a different story, though. It is a volatile pitch, responsible for 26 strikeouts but opposing batters have also taken him deep on it 3 times (compared to two each for the curveball and fastball), have walked 6 times, and are batting .283 and slugging .402 against the slider this season, compared to a career .252 slugging percentage against the slider. That said, opposing batters are not necessarily avoiding it, they are swinging at it 56.9% of sliders thrown in 2017 compared to 56.2% of sliders thrown in his career. So he’s throwing it harder, but it isn’t as accurate, either too far down and away to a left-handed hitter, or just high enough in the zone that it is hittable.

This isn’t a smear job on Kershaw, but it’s just so weird. He’s still nearly unhittable, but it’s his traditionally most unhittable pitch that is coming back to hurt him. He’s allowing home runs at twice his career rate, but he’s also limiting walks at a career best rate and 2nd best in the NL rate. Behind the league leading WHIP and career best K/BB ratio, it’s hard to notice that his home runs are ballooning, but I think we’ve found a reason. If this continues, he could allow more than 25 home runs this season. That’s like 13th in the National League, a seat next to Jason Hammel!

Gotta get that slider down! 

Much like this. He’s still the best pitcher in the game by a considerable margin, and when he is handed his fourth Cy Young Award in November, we can go back to this post and laugh at me. Or applaud me because we diagnosed Kershaw’s home run “problem”.

Thanks for reading.

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