Caleb Kilian’s Debut Taught Us Something New and Important About His Sinker

A lot of what makes top Chicago Cubs pitching prospect Caleb Kilian special is apparent right away when you watch him: the build, the velocity, the strikeout stuff. He checks the obvious boxes we look for in a good Major League starting pitcher. We’ll get to see him make big league start number two tonight against the Padres.

When I looked back at Kilian’s debut, a lot fit right in line with my expectations. The usage of his arsenal mirrored what I wrote in his preview: sinkers and cutters early in at-bats, four seamers and curveballs when he got to two strikes. Even during his perfect first three innings, I saw the feel of the cutter wasn’t there, and that led to the problems of the fourth inning. It was, honestly, a fairly cut and dry Kilian outing from an evaluative standpoint as you watched.

But MLB debuts also allow the opportunity to align prior beliefs with Statcast metrics – things we might not see while watching live – and there was something under Kilian’s hood that I want to highlight, because it surprised me. His sinker has an extra thing going for it: seam-shifted wake.

We’ve talked about SSW a few times in this space over the years, as it went from a Barton Smith theory to common parlance inside baseball. When oriented in the right way, the seams on a baseball can create additional, unexpected movement as it moves through the air. That can certainly help to fool hitters and stay off the barrel, and some pitchers (Kyle Hendricks being a prominent one) see more effect from this than others. There is a movement inside baseball right now to weaponize seam-shifted wake, but as writers, we’re largely still in the phase of just identifying these players that receive extra benefit.

And after his debut, I think we can confidently say that Caleb Kilian is one of them.

At Baseball Savant, seam-shifted wake is captured using the difference in two types of spin-direction that they measure: out of the pitcher’s hand, and when the ball reaches the plate. The more deviation we see in spin direction between these two measurements, the more we can surmise the pitcher is having seam-shifted wake influence (particularly on fastballs). If you think of a clock, Kyle Hendricks’ sinker starts by spinning at a 12:45 axis (from the pitcher’s POV), and gets to the plate spinning at a 2:00 axis. Hendricks has both low spin rate (1885 rpm) and low active spin (83%) on his sinker, so a lot of what makes that pitch interesting is that axis deviation. (Brett: This concept goes a long way to explaining how certain pitchers with two-seamers/sinkers that looked relatively uninteresting by the spin data wind up being so effective.)

Among RHP that have thrown 100 sinkers this year, only 11 have at least a 75 “minute” deviation in the spin directions of the pitch. That is the amount of deviation that Kilian’s sinker showed in the 43 times he threw the pitch in his debut, showing both the low spin (1990 rpm) and low active spin (77%) that are common in seam-shifted wake sinkers.

The big difference between Hendricks’ and Kilian’s sinkers, of course, is velocity. You know where Hendricks sits, but Kilian averaged 93.3 mph with the pitch against the Cardinals. I think the better comparison is between Kilian and Noah Syndergaard, another big right-hander who throws 94 mph sinkers with big axis deviation (Noah’s is 60 “minutes”). Both guys have really similar movement profiles on the pitch, too. And Syndergaard’s sinker is among the best pitches in baseball this season, producing nine runs of value off a .185 wOBA allowed, per Savant. (Brett, sliding in again: hey, think maybe Syndergaard is the kind of pitcher the Cubs might plan to give a look in free agency? He isn’t striking ANYONE out anymore, and is getting “lucky” by the data, but my gut says he’s exactly the kind of guy the Cubs would love to work with.)

As Kilian moves forward in his career, learning to weaponize that sinker like Syndergaard has is perhaps the lowest-hanging fruit in seeing him achieve his ceiling. This takes good command to the arm-side third of the plate, and will take a less generic usage profile than Kilian showed in his debut. But the foundation is there, and given the new information we learned, I’m more confident than before his debut that the Cubs have a Major League starter in their top pitching prospect.

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