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Colorado Rockies prospects: No. 23, Michael Prosecky

The right-hander was drafted in the sixth round of the 2022 draft and has been slowly transitioning from closer to starter

23. Michael Prosecky (141 points, 17 ballots)

When the Rockies signed Prosecky to a slightly over-slot $300k bonus after drafting him in the sixth round in 2022, most observers thought the left-handed pitcher would be ticketed for the bullpen. After all, that’s where the 6’3” hurler had made his bones in college as Louisville’s closer. Instead, the 22-year-old made the transition to the starting rotation in his first-full professional season and it went quite well.

Pitching at a league-average age at Low-A Fresno, Prosecky averaged over five innings per start (109 of them in 21 starts) and looked no worse for the wear, never eclipsing 100 pitches in the process. Prosecky posted a 2.72 ERA (4.07 xFIP) with a 1.17 WHIP, 10.3 K/9 rate, and 3.4 BB/9 rate on the season.

Not only did Prosecky succeed in the rotation, he maintained an elevated strikeout rate while lowering the walk rate well below what he displayed in college. Though it appears Prosecky is in need of higher-level competition, it’s good to see a Rockies pitching prospect be both healthy and effective for an extended period of time.

Here’s Prosecky striking out the side in early June 2023, courtesy of

FanGraphs jumped Prosecky up to near the top of the 40 FV tier in their mid-season 2023 evaluation, 17th in the system on the strength of a 55-grade curveball:

The southpaw has a short, vertical arm stroke that helps his heater play as an in-zone bat misser despite average velocity. He hides the ball forever and it appears to jump on hitters very quickly. Off of that he throws a classic 12-to-6 curveball, which is virtually indistinguishable from his fastball until it starts to bend with huge, bat-missing depth. Those two pitches give Prosecky a reliever’s foundation. He’s a bit of a short strider and his arm stroke isn’t always well-timed, but so far Prosecky has thrown enough strikes to continue developing as a starter. His third pitch is currently a changeup, which is still below average but has long-term ceiling because of the whip of Prosecky’s arm stroke. It’s perhaps more likely that his ability to spin it leads to a second type of breaker, like a two-planed slider. Either way, Prosecky is probably just scratching the surface of a third offering because of his collegiate role.

The median projection for Prosecky is probably still that of a backend starter, and it’s tough to rank him ahead of players with a similar profile who are younger, closer to the big leagues, or both. But of all the 40 FV pitchers in this layer of the Rockies system, he’s the one with the best chance to make a leap over the next 12 months because of his malleability.

While doesn’t list Prosecky on their Colorado top 30, he was ranked 180th in his draft class as a 40 FV pitcher, hinting at a future starting role:

Prosecky has more velocity than most left-handers, operating with a 92-95 mph fastball that tops out at 97 with some riding action. He works heavily off his heater, backing it up with a mid-70s curveball that can get swings and misses but also eludes the strike zone too frequently. He also has a firm mid-80s changeup with modest life but doesn’t use it much as a reliever.

With the potential for three average or better offerings, a strong 6-foot-3 frame and a delivery with no glaring flaws, Prosecky may tempt a pro team to try him as a starter. To succeed in the rotation, he’ll have to use his secondary pitches and significantly improve his control. It’s more likely that he’ll wind up in the bullpen, where his role will depend on his ability to locate his fastball and curve.

Prosecky was a pleasant player development surprise for the Rockies in 2023 thanks to his jump up the pitcher role value spectrum and effectiveness in the role. His stuff got Low-A hitters out, but the question will be if he can sustain a starter’s workload with that arsenal as he moves up the minor league ladder — I suspect he’ll pitch in High-A Spokane this season. The FanGraphs write-up was enough to convince me Prosecky stood out from a lot of other pitching prospects in the system. I ranked him 23rd on my ballot with a 40 FV designation.