Alex Cobb is leaning on his curveball

Pitchers tend to become known by their signature pitch. Chris Archer is a slider machine, Rich Hill pitches backwards with his looping curveball, and Dallas Keuchel generates a ton of ground balls with his worm-killing sinker. Until this season, if asked to identify what pitch is synonymous with Rays starter Alex Cobb, the answer would’ve been his split-change.

(Note: Curiously, Baseball Savant had it classified as a changeup last season, but as a split-finger this season. In interviews, Cobb refers to it as a changeup. But from this point forward, we’re gonna call it a splitter because that’s what it’s classified as by Pitch Info and Baseball Savant in 2017. It’s semantics; we’re talking about one pitch.)

The splitter is rare in today’s game. According to FanGraph’s pitch type designations from Pitch Info, only 6 qualified starters in baseball are throwing the pitch more than 10 percent of the time. While Cobb’s name is among those six pitchers, he’s drastically reduced the number of splitters he’s thrown this year. It’s no longer his calling card.

Chart via FanGraphs

As with most starters, there have been ebbs and flows to Cobb’s pitch mix from start to start, but the splitter has always been his primary breaking pitch — until this year. In 2017, Cobb’s splitter usage has dropped from 29.3 to 16.6 percent, while his curveball usage has increased from 22.5 to 32.7 percent.

The usage shift was noticeable early on in the season and detailed by Eno Sarris of FanGraphs, Marc Topkin of the Tampa Bay Times, and Beyond the Box Score’s very own Jim Turvey at DRays Bay. Shortly after the flurry of articles regarding his missing splitter, David Laurila of FanGraphs spoke with Cobb about why it was no longer at the forefront of his repertoire post-Tommy John Surgery.

“Getting your muscle memory right where you want it takes some time. I think that’s why the changeup is usually the last pitch to come. The other pitches aren’t affected as much by the minor movements it takes to make a successful changeup.”

In that same piece Cobb expressed hope that he would regain feel for the pitch over time.

“I wouldn’t necessarily say I’m waiting for my changeup to come back, but I’ll know when it does. I’ve used the same grip — it’s a split grip — basically my whole professional career, so I know what everything feels like. Once I get it right, it will click.”

Cobb has thrown more splitters than curveballs in three of his 23 starts this season, and thrown them equally in two. We might be able to infer that on those days, he had a better feel for the pitch than normal, but that it hasn’t lasted for the entirety of the season.

Since his return from Tommy John, Cobb’s splitter has the same velocity that is has always had, and similar horizontal movement. The most noticeable difference is that Cobb is getting much less vertical movement on the pitch.

Chart via Brooks Baseball

It’s not mirroring his fastball and sinker exactly, but there’s much less separation than there used to be. Relatedly, he seems to have lost his vertical release point on the offering.

Chart via Brooks Baseball

His release point seemingly started to drift in 2014 — pre-surgery — but has been totally separate from his other three pitches this season. The lack of drop on Cobb’s splitter has seen the swinging strike rate drop just over 6 percentage points from his prime 2013 and 2014 seasons. Batters have a .348 wOBA against the pitch this season, compared to .218 in 2014.

So, Cobb’s splitter hasn’t been what it once was, and instead of forcing it, he has shifted strategy to utilize his curveball more. It’s great to see a willingness to adapt, and the change hasn’t hurt Cobb’s overall production much. In his first full season back from Tommy John surgery, he has earned a 3.80 ERA, 4.30 FIP, and 4.05 DRA in 147 innings to this point.

The most noticeable shift is not in his outcomes, but in the way he’s achieving these results. Cobb’s strikeout rate is a meager 15.8 percent, well below his outstanding 23.2 and 21.9 percent rates from the pre-Tommy John standout seasons of 2013 and 2014. He hasn’t become an extreme ground ball pitcher either; in fact, his 45.7 percent ground-ball rate is the lowest of his career, by far. He’s never before dropped below 50 percent until this season.

Cobb’s strikeouts and ground balls are down while his fly balls are up. Add to that the fact that he’s allowing the highest hard-hit rate of his career — 37.6 percent — and his success this season is a bit of a head scratcher. What is it about Cobb’s curveball that has allowed it to step in and fill the void left by his splitter?

Here’s a chart featuring the every pitcher who’s had at least 50 curveballs put into play this year, and the wOBA and exit velocity allowed against the pitch.

Chart via Baseball Savant

Cobb’s curve gets hit harder than all but two other pitchers who qualified, and yet it’s wOBA against is below .300. That’s because when hitters are making contact with it, they are either pounding it into the ground or popping it up. Cobb has a 35.3 percent infield-fly-ball rate on his curveball this season. When batters have been able to put it in the air, they are getting under it too much.

Chart via Baseball Savant

Only six of the 162 balls put in play against Cobb’s curveball have been classified as a “Barrel’ or even as “Solid Contact” by Baseball Savant. He’s only given up one home run on the pitch and that was to Aaron Judge, who — in case you hadn’t heard — is pretty skilled at mashing taters.

Alex Cobb is currently on the disabled list but is slated to return next week. There’s no telling if his dominant splitter will come back into the fold as well. But while he waits for it to resurface, the curveball is doing a dynamite job filling in as his main breaking pitch.

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Chris Anders is a featured writer at Beyond the Box Score. You can find him on Twitter @MrChrisAnders.