The Big Question That Will Decide Whether Jacob Misiorowski is a Starter or Reliever This Spring

[Matthew Trueblood]

It was an encouraging 2024 season for the Brewers' top pitching prospect, who got close enough to the big leagues to knock on the door thereto. Can he get there as a starting pitcher?

Image courtesy of © Curt Hogg / USA TODAY NETWORK

After his promotion to Triple-A Nashville in the second half of 2024, Jacob Misiorowski transitioned from the starting role he had occupied at Double-A Biloxi to a late-game relief gig. For as long as he has been on the prospect radar, everyone has understood the fact that Misiorowski might end up in the bullpen anyway, and in the heat of the Brewers' push to a second straight division title and a looming playoff run, it seemed clear that Misiorowski's greatest short-term value was as a high-octane, high-leverage, short-burst flamethrower.

In 14 appearances totaling 18 innings, Misiorowski certainly showed off the potency of his raw stuff. Opponents only managed five hits against him. He struck out 22 of the 70 batters he faced. On the other hand, though, he walked 10 of those batters, and he hit another three with pitches. Control is the big limiting factor for Misiorowski, whose stuff can be overpowering. In fact, after seeing him work in an intense role at the highest rung of the minor-league ladder, it's fair to wonder whether it will be the thing that pushes him to the pen—or the very reason why it's important that he stays in the rotation.

Misiorowski's fastball sat at 98 miles per hour during his stint with Nashville, reflecting the ability to cut it loose each time in short appearances. The pitch still doesn't have elite vertical or horizontal movement, but it should have plenty of carry to baffle hitters when he can keep its velocity in the upper reaches of the 90s, given the relatively low slot from which he pitches. In the limited sample (his time with Nashville) for which we have detailed pitch data, he appears to be capable of filling up the zone with the heater, and to have a plan for it: he attacks the glove side, away from right-handed batters, quite well for a pitcher with this fastball shape. Combined with his velocity and extension, his ability to locate that pitch as he already did should be good enough to make his heater dominant.

Misiorowski also showed a feel for locating his curveball, a pitch with plenty of velocity separation from the fastball and good vertical depth. He can hit the bottom of the zone with that offering, or drop it below the zone to induce chases.

It's not as refined a secondary weapon as you'd like a starter to have, but it's a potent pitch already. As sped-up as hitters have to be when facing what is effectively a triple-digit fastball, that curve can devastate opponents.

That leaves his slider, though, and that's the pitch we need to talk about.

Whipsawing in at almost 93 miles per hour when he worked in short relief, the cutterish slider is a pitch that has the potential to make Misiorowski an ace starter, but only if he can get it under some semblance of control. Right now, or at least during his brief time in Triple A, Misiorowski can't locate that pitch competitively, and batters don't have to respect it. That will make it much easier for hitters to sit on one of his two main offerings, and give them more of a chance to handle him, especially if stretching back out as a starter takes a tick or two back off of his fastball.

The key question, then, is this: Can Misiorowski modulate the effort in his delivery enough to exercise better control of his slider, when pacing himself to last in a game as a starter? If so, he's a candidate to be in an MLB rotation very soon, and to be superb there almost right away. If the slider/cutter is a pitch he can corral with just a bit more proprioception, and if that doesn't come at an undue cost to his fastball velocity and his overall execution of the three-pitch repertoire, then he's a star. However, if the slider remains this erratic, then so will Misiorowski. He'll be confined to the bullpen, and while that might be his fastest track to the majors, it will slightly reduce the impact he can have for the Brewers. Come spring training, we need to keep a close eye on his efforts to command the slider.

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[jay87shot]

I think I would start Misi out as a starter regardless of how he looks in spring training in AAA. If he looks good 10% or less bb rate, I am all for getting him into the bigs rotation earlier rather than later. If his control is a little spotty like last year, 10-13% bb rate, I would like to find him a multi-inning piggyback role especially if we are at a 6 man rotation at that point and decide what his role is next offseason. If control goes backwards, at about mid-way I would transition him to a late-inning relief role and look to get him some big league innings in September to see if he can help potentially in the playoffs.

Wonderful write up by the way.

[Michael Trzinski]

Proprioception? @Matthew Truebloodyou crack me up. Makes me want to work on my body control 🙋‍♂️