The Evolution of Corey Kluber's Curvenball

Dominant as ever, Corey Kluber perplexed White Sox hitters on Friday. The Indians bona fide Ace continues to evolve as a pitcher, and is relying on the American League’s best curveball to do so. The IBI's Gage Will explains how.

As three true outcome baseball - plate appearances that end in a walk, strike out, or home run - continues to become more prevalent, pitchers who excel at missing bats, and have plus control, will continue to reap the rewards. This includes Corey Kluber.

We’ve gotten to know Kluber as an elite starter over the past three years. There have been mostly ups, capitalized by the 2014 Cy Young award, and seldom lows. How he has ascended to that prolific elite status is no secret – by generating whiffs. He is no mystery to American league hitters at this point, which has warranted some evolution on his part to continue generating the ever-important swing and miss.

Friday night’s evisceration of White Sox hitters offered some insight into this evolution. Kluber had Chicago hitters off balance throughout the night. There were even a few moments where he elicited audible “Wow” reactions from me. As a resident nerd and former subpar high school catcher, I was most impressed with his pitch sequencing, especially in three at-bats.

2nd inning – Avisail Garcia

These were three nasty sliders, generating three whiffs. Kluber toyed with Garcia, playing into his aggressive nature at the plate.  As you can see, none of these offerings were in the zone. Throughout his career Garcia has swung at about 42% of pitches out of the strike zone, while the “average” major league hitter only offers at about 30% of such pitches. The first pitch was down and away, followed by one up in the zone to change the eye level, and then another down and away to finish him off. Masterful game plan and execution.

8th inning – Yolmer Sanchez

Have you ever told a friend to get in the car, only to slightly move the car forward as he reaches for the handle? That was this at-bat. Kluber peeled off a get-ahead curveball on the first pitch. Sanchez demonstrated he wanted nothing to do with that pitch, so Kluber followed with the same exact pitch. Yolmer decided to window shop some more. Strike two. Feeling his curveball now, Kluber lowered the eye level with a sharp bender that finished around the bottom of the zone for a swinging strike three. Throwing a major league hitter three straight curveballs in the zone would probably be considered taunting over in the NFL.

9th inning – Jacob May

Location, location, location. Oh, and three different pitch types. Kluber started May on the inside corner with a slider for a called strike. The next pitch was a changeup on the opposite corner for strike two. Finally, Kluber unleashed the pitch of the night. It was a vintage Kluber two-seam fastball that started on the inside corner and released all the way to the outside corner, producing a swinging strike three. This ball darted about twelve inches, at 93 miles per hour. For Jacob May, it was unhittable.

As I dove into this game, I noticed the sheer volume of curveballs thrown by Kluber. One-fourth of his offerings were curveballs. A trend has set in over the past few years. Kluber has utilized the bender much more often than early in his career.

Not only is Kluber relying on the curveball more, it has become very effective. It leaped in effectiveness from 2013 to 2014, which coincided with his coming out party. 2016 may have been Klubot’s best curveball year yet, though.  FanGraphs recently ran a column grading all American League curveballs. Can you guess who had the most effective one? Last year, Kluber’s curveball generated a whiff rate of 27%. The next best whiff rate? 17.6%.

We have very little data on pitch usage through only four starts. The curveball percentage is still worth tracking, especially considering the reports that Kluber was apprehensive about throwing breaking balls in his first start of the year at Texas. As we continue to watch Kluber miss bats, the amount of curveballs he chooses to utilize will be an interesting storyline.

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