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Smash or Pass: Mitch Keller

He hasn't quite put everything together yet, but he’s close.

MLB: Pittsburgh Pirates at Boston Red Sox Eric Canha-USA TODAY Sports

Who is he and where does he come from?

He’s 2023 all-star Mitch Keller, and he’s currently employed by the Pittsburgh Pirates. He made his major league debut in 2019 and has been with the big league club since then, outside of a brief demotion in 2021.

Is he any good?

I truly don’t know how to answer that question. When he was coming through the minor leagues, he was a top prospect, throwing 99 MPH fastballs, racking up strikeouts, and posting great numbers at every level. When he got the call to the majors in 2019, he struggled, lost his confidence, and looked like a bust.

After a terrible 2019, throwing only 21 innings in 2020, and another awful 2021 season, Keller went to Tread Athletics to revive his career. At Tread, he worked to increase his velocity, correct his mechanics, and regain his confidence. His offseason work paid off, as he pitched his way to a 3.91 ERA in 29 starts in 2022. Looking for more improvement, he spent another offseason working with Tread to add to his repertoire, adding a cutter to an already broad pitch mix.

So in 2023, he put it all together and finally broke out, right?

Well, it certainly looked like he had it together at the beginning of the year. He came into the year throwing high 90s fastballs, spotting his off-speed pitches well, and utilizing his entire arsenal to get outs. He pitched his way to an all-star appearance, and it appeared the Keller had finally arrived.

But then, after the all-star break, something happened. The cutter he used so effectively in the first half started getting crushed. His velocity dipped and he stopped getting so many strikeouts. He was never put on the IL, and he was never jumped in the rotation. To me, it looks like he just ran out of gas. 194 innings was 40 more than his previous career high; it seemed to have taken its toll.

You still haven’t answered the question.

I’m going to say yes. Down the stretch, he was hit around a bit as he ran out of gas. Even as he struggled, he was able to put together a few really good starts, including two separate eight-inning shutout outings. I also think he has another level. Pitch models absolutely love his sweeper (142 Stuff+), but it hasn’t returned great results. Improving that pitch could turn him from a solid pitcher into a legitimate star. Keller is still only 27 and has time to grow as a pitcher.

Why would he be a good fit for the 2024 Red Sox?

He has legitimate strikeout stuff. Aside from Chris Sale at his best, there’s nobody in the Red Sox rotation with proven strikeout stuff. Nick Pivetta has shown the ability, but he’s yet to prove he can be consistent through an entire season. Craig Breslow has mentioned developing pitchers with the ability to create whiffs in the strike zone. Keller can do exactly that with his fastball. At his best, he can reach the high 90s with his fastball, complemented by a bevy of offspeed pitches. His 25.5% strikeout rate would have been good for third in the rotation, behind only Pivetta and Chris Sale. Given the current state of the Red Sox defense, a pitcher who can strike out 200 batters in a season is a welcome addition.

Why would he not be a good fit for the 2024 Red Sox?

The Red Sox need pitching, and Keller is far from a sure thing. He’s shown his ability as an athlete, touching 101 MPH in a bullpen session, but that hasn’t directly translated into results. While he’s incredibly talented, the Red Sox need pitching now. Betting on a breakout that never happens would be a significant blow to the rotation.

Is he available?

Keller still has two years of arbitration left, so the Pirates may be inclined to hang onto him for another year. Bryan Reynolds was in a similar contract situation when they signed him to the largest contract extension in Pirates history, an 8-year, $106.75MM deal. They also signed Ke’Bryan Hayes to a pre-arbitration extension. They had talks with Keller during the season, yet he remains on his rookie deal. The longer they wait, the more expensive it will be, and the less incentive there is for Keller to sign before hitting the open market. It’s hard to see the Pirates all of a sudden becoming big spenders, so they may be inclined to move Keller while he still has some control to maximize the return.

What will he cost?

The closest comparison I can think of is the Rays’ trading for Aaron Civale. It cost them Kyle Manzardo, an advanced prospect with a bright future. Keller would likely be a bit cheaper, given that it isn’t a mid-season trade, but the Pirates will look for talent that's close to debuting, if not already in the majors. I don’t want to name anyone specifically because that would be baseless speculation, but maybe one of the many young outfielders gets the deal done?

Show me a cool highlight.

Here’s something a little different. It’s a video of Keller working in the off-season at Tread Athletics. Take a look at the process behind learning a new pitch. There’s a full hour-long video about Keller’s journey in the majors too, if you’re into that kind of thing.

Smash or pass?

There’s some risk involved with Keller; his career has yo-yoed between highs and lows. Still, I think now is the time to buy. He’s spent the last two offseasons refining his repertoire and learning who is he as a pitcher. This year, he ran into issues as he tired through the season. If he’s going back to Tread Athletics or Driveline, there’s a good chance they’ll work on a program to keep his velocity up through the season. He’s incredibly talented and has the drive to make it put it all together. I’m buying a Keller breakout, and think the Red Sox should too.