25. Michael Prosecky (89 points, 12 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 distinguished himself in college as Louisville’s closer. Instead, the now 24-year-old made the transition to the starting rotation in his first full professional season and has stayed there ever since. As a prospect, Prosecky pairs a deceptive low to mid-90s fastball with a high spin rate curveball, slider, and change-up.
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Mid-season 2025 Rank: HM
High Ballot: 20
Mode Ballot: 21, 22, 24, 25
Future Value: 35+, starting pitcher depth
Contract Status: 2022 Sixth Round, University of Louisville, Rule 5 Eligible, three options remaining
MLB ETA: 2026
After a strong 2023 spent in Low-A Fresno, Prosecky was delayed by elbow inflammation in 2024 until mid-June, which limited him to 48 2/3 innings across 14 games for a combination of the ACL team, Low-A, and High-A. The good news was that he struck out a sterling 14.4 batters per nine innings, albeit against younger competition. Prosecky also received an Arizona Fall League valedictory, where he threw an additional 15 1⁄3 innings with poor run suppression numbers (7.63 ERA, 2.02 WHIP, and 5.3 BB/9 rate) and strong strikeout numbers (13.5 K/9 rate). All told, across 22 appearances in four leagues in 2024, Prosecky ended up with 101 strikeouts in 64 innings pitched (14.2 K/9 rate), 30 walks (4.2 BB/9 rate), and 37 earned runs allowed (5.20 ERA).
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In 2025, Prosecky went back to High-A Spokane, where he was 0.8 years older than league average. He stayed healthy and threw 88 2/3 frames of 3.86 ERA ball in 18 starts with a 1.26 WHIP, 9.4 K/9 rate, and 4.2 BB/9 rate. That’s a significant K/9 rate drop, but the run prevention numbers improved enough to earn Prosecky a post All-Star break promotion to Double-A Hartford, where he was 0.7 years younger than league average. In nine starts with Hartford, Prosecky posted a 4.97 ERA (4.81 xFIP) in 38 innings built on his 1.55 WHIP, 8.1 K/9 rate, and 5.4 BB/9 rate. Overall, it was nice to see Prosecky succeed against upper minors hitting.
Here’s Prosecky striking out ten in a start for Spokane last year:
Prosecky is ranked 22nd in the system by MLB Pipeline as a 40 FV player:
The 6-foot-3 left-hander does have the size and repertoire to potentially start, with a four-pitch mix. At his best, he runs his fastball up to 95-96 mph and can command it well, missing bats with it along the way. He has a slider that has late action with depth, a slower curve that he can use to steal a strike and an improving feel for his changeup as well.
Prosecky had thrown just 64 innings in college before topping 100 IP in 2023. The Rockies are hopeful that a now completely healthy Prosecky, who has generally been around the zone when he’s at his best, can hit the reset switch and start moving up the ladder again in 2025.
Eric Longenhagen of FanGraphs ranked Prosecky in the 35+ FV tier and 30th in the system on the strength of a 60 future grade curveball:
Prosecky only sits 91-93 mph, but hitters don’t seem to pick it up. The southpaw has a short, vertical arm stroke that helps his heater play as an in-zone bat misser despite below-average velocity. He hides the ball forever and it appears to jump on hitters very quickly. He throws a classic 12-to-6 curveball off of that, a pitch that’s virtually indistinguishable from his fastball until it starts to bend with huge, bat-missing depth. Those two pitches give Prosecky a lower-leverage reliever’s foundation. Prosecky’s arm stroke isn’t always well timed, and his strike-throwing results have been mixed during this try as a starter. In the 2024 Fall League, Prosecky was working with a second breaking ball, a slider in the 82-84 mph range that looked below average. There’s definitely more variance here than is typical for a guy who sits 92, but Prosecky is tracking like a low-leverage lefty.
Baseball Prospectus ranked Prosecky 20th in the system last January:
Prosecky fails to light up the radar gun but gets by thanks to plus carry on a low-90s heater. With a four-pitch mix, Prosecky has more of a typical starter’s repertoire. What he lacks is reps, as a reliever in college who then missed time due to injury. Colorado sent him to the Arizona Fall League, where he continued to miss bats but also yielded runs in an environment more friendly to older hitters. A full-health season would see Prosecky end next year having handled a decent chunk of time in Hartford, continuing to miss bats. His floor is lofty as a bullpen piece, but as long as he seems startable he’s performed enough to merit the looks.
Keith Law of the Athletic ranked Prosecky 14th in the org last February:
Prosecky was my sleeper for the Rockies last year, but after he went to an outside lab to try to boost his velocity, he came down with elbow inflammation and never got on track, throwing 63 innings total between the regular season and Arizona Fall League, with terrible results in the fall and in High A. Even when he did pitch, he was 90-94, down from 92-95 the year earlier; he barely used his slider; and his command was way off. When healthy, he’s got a four-pitch mix, with the slider his best offering and a changeup that could flash plus but didn’t sit there. There’s deception in his delivery to help the fastball play up as well, as long as he’s locating it. Let’s hope a full offseason of rest gets him back to his 2023 form, when he looked like he might be a mid-rotation starter.
It’s interesting to see the difference in evaluation on the curveball — for Law and MLB Pipeline, it’s Prosecky’s weakest pitch but for Longenhagen, it’s his best.
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Prosecky has been a pleasant player-development surprise for the Rockies thanks to his jump up the pitcher role value spectrum and effectiveness in the role. He missed fewer bats in 2025 but took a step forward in run prevention at a higher level while throwing 126 2/3 innings. The Rockies didn’t protect Prosecky from the Rule 5 Draft this off-season but he wasn’t selected, so he will likely return to Hartford to begin 2026 and he will be a big league rotation option later in the season. I ranked Prosecky in the middle of my 35+ FV tier, 29th on my list.
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