Change coming? Inside the analytics of Keller's resurgent pitch

BRADENTON, Fla. -- Mitch Keller is a man of many pitches. It¡¯s a good thing PitchComs are the norm now because there aren¡¯t catchers with enough fingers to call his seven pitches: a four-seam fastball, sinker, slider, sweeper, cutter, curveball and changeup, his least-used pitch in 2024.

Keller threw that changeup 0.7% of the time last season, just 21 times in total. He¡¯s already thrown it more times this spring: 29, once you count his nine such pitches against the Orioles in the Pirates' 6-3 loss Monday night. After throwing it less than 1% of the time last year, he¡¯s using it nearly 15% this spring.

"It honestly feels like 50% just from the drastic changes of using it a lot,¡± Keller said with a chuckle. ¡°Super happy with it.¡±

The changeup has always been part of Keller¡¯s repertoire in the Majors, but there was only one year that he threw it at least 5% of the time (2022). It¡¯s also never been that productive of a pitch. Except for the 2020 season, hitters have always posted a season batting average well north of .300 against the changeup, so it makes sense why he placed it on the back burner, often going with his cutter instead.

This isn¡¯t the same changeup as last year, though. Keller went into the lab to reprofile how it moves, and on Monday, it averaged 0 inches of inverted vertical break (IVB). Unlike most things in baseball, zero is a good thing in this context because IVB measures the movement a pitch experiences due to spin. Getting zero -- or negative -- inches means that he¡¯s effectively killing the spin and giving the illusion of drop to the hitter.

Or, to put it in simpler terms, the pitch just got a lot nastier. Last year, he averaged 4 inches of IVB. Left-handed hitters are going to have a new-look, revitalized pitch to watch out for this season.

But there¡¯s part two of Keller¡¯s Spring Training pitch mix shakeup. Last year, he threw the cutter 12.2% of the time. He has thrown it just once this spring, and that was Monday. The changeup usage is rising, and many of those new pitches were in situations where he threw cutters last year.

"I think just analyzing what happened last year and where it's at, the more that I can protect it a little bit is better,¡± Keller said. ¡°So taking changeup usage up, cutter down, maybe [it will] help protect both of them.¡±

¡°Protect¡± may be the key word because there were situations last year where Keller thought hitters could sit on his cutter, especially when they were ahead in the count. Going by pitch usage, his cutter was his second-most used pitch last year when a left-handed hitter was ahead in the count, and it didn¡¯t really work. The whiff rate was high (26.3%), but the batting average against was higher (.444). The cutter didn¡¯t yield the results it needed against left-handers late in the year, and struggles against lefties were a big factor for why Keller slipped in the second half.

¡°I think that just got me in bad positions,¡± Keller said. ¡°I had to really be perfect with it. So I think using it not as much will give me some more room to not be as perfect with it."

A two-pitch approach against left-handed hitters could be beneficial. At the end of last season, Keller vowed to make a ¡°full encompassing¡± look at his body of work to try to explain why he teetered off at the end. Keeping southpaws in check would be a major development for 2025.

¡°They're gonna pair because, obviously, they're moving in different directions,¡± Pirates manager Derek Shelton said about the cutter and changeup. ¡°I think the evolution of the changeup just continues to get better, which is going to be another weapon for him against left-handers."