Clayton Kershaw’s New Toy

At an age when most young hurlers are hopping a Greyhound bus from Inland Empire to Rancho Cucamonga, Clayton Kershaw is starting pivotal playoff games for a Dodgers club seeking its first World Series title since, well, Clayton was born.

The fifth inning of Kershaw’s NLCS game one start highlighted that he is still in the nascent stages of his career. The 6-3 power lefty did walk 4.8 batters per nine innings during the regular season, with a 55.6 first-pitch strike percentage (58.2% MLB average).

Yet despite those occasional bumpy moments, Kershaw has proven capable of quashing opposing lineups. He punched out 9.74 hitters per nine frames, the 7th-highest rate among starters tossing 150+ innings.

Kershaw was extremely tough to hit on pitches within the zone, with an 83.3 Z-Contact% that ranked 6th among starters (the MLB average is 87.8%). And when batters were fortunate enough to make contact, they often popped the ball up, with a 13.5 infield/fly ball percentage (7th among starters).

Most fans know Kershaw for two things: searing fastball velocity and a slow curveball so dastardly, Vin Scully dubbed it Public Enemy Number One.

To be sure, both of those pitches are electric. Kershaw’s run values are a little inflated due to a very low HR/FB rate (4.1%)- some balls that probably should have left yard stayed in, boosting those linear values. But still, his 94 MPH gas was worth +1.48 runs per 100 pitches (third best in baseball). That 73 MPH yellow hammer was similarly effective, with a +1.54 mark. Clayton would rather not talk about his seldom-used changeup, though (-1.78).

But did you know that, since June, Kershaw has integrated yet another quality breaking pitch into his arsenal? Take a look at his pitch usage by month:


Fastball (FB) 79%, Curveball (CB) 15%, Changeup (CH) 6%


FB 73%, CB 20%, CH 7%


FB 72%, Slider (SL) 8%, CB 15%, CH 5%


FB 69%, SL 10%, CB 18%, CH 3%


FB 67%, SL 11%, CB 20%, CH 2%


FB 72%, SL 16%, CB 11%, CH 1%

Gradually, Kershaw has added more 81 MPH sliders into the mix. The pitch is fascinating, in terms of how it moves in relation to his world famous curveball. Looking at Clayton’s Pitch F/X data, we see that his new toy breaks away from lefties (in to righties) an average of 4.8 inches. Kershaw’s curveball has similar horizontal movement, breaking away from southpaws 4.1 inches. That curve, of course, has plenty of vertical “drop”, falling 6.8 inches more than a pitch thrown without spin.

Kershaw’s slider creates an interesting dynamic for hitters. They see a big, bending breaker coming toward the plate, but which is it? As an example of how difficult finding that answer might be, here are Kershaw’s release and movement charts from his 10/3 start against the Rockies (his last regular-season start):

Release Point:


In this start, Kershaw’s release gave away nothing to the opposition. And, you can see how much the slider and curve mirror each other in terms of horizontal break. Looking at this another way, here’s Clayton’s flight path chart for October, courtesy of Trip Somers’ Pitch F/X tool:


This is a bird’s-eye view of Kershaw’s pitches as they head toward home plate. The flight path of the slider and the curve overlap. Same release point. Same flight path. The poor batter probably won’t know what’s coming until it’s too late.

Overall, Kershaw’s slider was worth +1.36 runs per 100 pitches during the regular season. And, as Somers’ amazing tool shows, the pitch has become an even bigger part of Clayton’s arsenal in the playoffs. Kershaw has gone to the slider 27 percent of the time in the NLDS and NLCS, throwing it for a strike almost 65 percent of the time.

I guess the only question left is, what will Vin Scully call this vicious breaking ball?

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A recent graduate of Duquesne University, David Golebiewski is a contributing writer for Fangraphs, The Pittsburgh Sports Report and Baseball Analytics. His work for Inside Edge Scouting Services has appeared on and, and he was a fantasy baseball columnist for Rotoworld from 2009-2010. He recently contributed an article on Mike Stanton's slugging to The Hardball Times Annual 2012. Contact David at and check out his work at Journalist For Hire.

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Brian Joura

Great stuff David!