Potanko: Keller’s Cutter Big Reason for Success

PITTSBURGH- When the Pittsburgh Pirates got off to their hot start during the 2023 season, many can attribute it to Mitch Keller’s rise to one of the best pitchers in MLB.

Keller started the season better than anyone expected, with an ERA of 2.90 in April and then 3.00 in May. Towards the tail end of May, Keller started to stumble while giving up ten earned runs combined on May 26 and May 31.

It seemed like Keller was spiraling in his first start in June, with five earned runs given up in 5.1 innings pitched against the Oakland Athletics.

In his most recent start on June 11, it seemed like Keller was facing a lot of outside pressure from the fans to get back on track to his April self, and he delivered tenfold.

Against the New York Mets, Keller delivered seven innings while only giving up two hits, one earned run, two walks, and struck out seven.

During that game, Keller seemed to have developed a very noticeable pattern.

Against a lefty-dominated lineup, Keller used his newfound cutter to the best of his ability doting the cutter on the edges and varying his speeds throughout the contest.

After his masterful effort against the Mets, Pirates manager Derek Shelton touched on Keller’s cutter.

“It’s become a weapon for him. I think we’ve seen the evolution of Mitch Keller not only with the sinker but with the cutter to combine with the curveball, the sweeper, and the changeup. When you’re adding pitches during the season, it shows your willingness to learn, which I think we all know Mitch does, and then your willingness to execute. [Hedges] did a really good job today with him in terms of what was working at a certain time and then being able to execute it.”

Shelton also touched on Keller varying speeds with the cutter.

“I think that’s the thing is that you get more in touch with it, you’re going to be able to do more things with it, and he’s starting to get the feel of that.”

Later on, after Shelton’s press conference, we trotted over to Keller’s locker to discuss his outing and how effective his cutter has been this season.

“To lefties especially, just getting something coming in on their hands. Then it just opens up my four-seamer away. They gotta decide what one – it’s either coming in on their hands or it’s coming away from them. I think that’s what makes it a difficult at-bat with those two pitches primarily. Then I have two other spin pitches I can throw for strikes which is really beneficial for me.”

With everyone discussing Keller’s sinker and newfound cutter, his sweeper has kind of gone under the radar as an effective pitch, especially against righties.

As it stands right now, Keller’s sweeper is holding opponents’ .220 batting average with an average exit velocity of 81.7 mph. In addition, Keller’s sweeper holds the highest whiff% out of all of his pitches with a 28.2% whiff rate.

“Going back to last year, it was a brand-new pitch for me,” said Keller. “Primarily using to righties, but now we’re using it to lefties. And I think that’s the big secret to it is being able to use it to left-handed batters too. Now it’s a four-pitch at-bat instead of a three-pitch. Just being more comfortable with it and being able to rip it for strikes. And then knowing when I want to go for the chase. Having that feel, it’s come really nicely throughout the year.”

What’s been clutch for Keller is limiting hard-hit balls.

In his previous years with the Pirates, Keller allowed a lot of hard-hit balls. In 2021 Keller’s hard hit% ranked in the third percentile, in 2022, Keller ranked in the 63rd percentile, and now in ’23, Keller remains near the top in the 89th percentile.

So we’ve seen a constant progression with Keller, and I think it gives a beacon of hope to not give up too fast on a pitcher.

Something we can attribute to Keller’s progression, albeit a slow one, has got to be the addition of his cutter and sweeper to his arsenal.

It will be interesting to see how Keller mixes his pitches against lefties and righties as the season goes on.