The left-hander is the first “consensus” PuRP on this list
25. Michael Prosecky (163 points, 18 ballots)
Prosecky marks the first player on this list that we could call a “consensus” Purple Row Prospect, as he was well clear of the vote totals of the previous five names. 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 23-year-old made the transition to the starting rotation in his first full professional season and it went well.
Pitching at a league-average age at Low-A Fresno in 2023, 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 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.
In 2024, Prosecky’s rise was slowed by elbow inflammation that shelved him until mid-June. He made four appearances for the ACL team, then he moved back to Low-A for two dominant starts (11 IP, 1 R, 5 H, 3 BB, 17 K) before finally making it to High-A Spokane in mid-July, where he was of league-average age. Prosecky made eight appearances (seven starts) for Spokane, throwing 29 innings with a 5.90 ERA (3.63 xFIP), 1.76 WHIP, 13.7 K/9 rate, and 5.3 BB/9 rate. Honestly the results in Spokane weren’t too concerning as Prosecky worked his way back to his 2023 form (and showed strong strikeout ability.
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).
Here’s Prosecky striking out six in the AFL this past fall:
Eric Longenhagen of Fangraphs ranked Prosecky in the 35+ FV tier and 34th in the system earlier this month 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.
Prosecky is ranked 17th in the system by MLB.com as a 45 FV player:
The 6-foot-3 left-hander has a potential four-pitch mix that could work in a rotation. He throws his fastball with late life in the 91-96 mph range, showing the ability to move it around the zone well. His slider has late action with depth and could eventually evolve into a solid out pitch and he throws a slower curve that’s more of a show-me, get-me-over type of offering. He has feel for a changeup and the Rockies are urging him to throw it more.
Considering how little Prosecky threw in college — a grand total of 64 innings in three years — he held up well over the course of a season and managed to surpass the century mark in innings pitched with plenty left in the tank while throwing better late in the year. He’s a solid strike-thrower who can finish hitters off late in counts who could stick in a rotation long-term if it clicks.
Law of the Athletic ranked Prosecky 9th in the org back in February 2024:
[In 2023 Prosecky] was 92-95 mph, touching 97, with a repeatable delivery that produces plus deception, pairing it with a sharp slider/cutter and a changeup that’s inconsistent but flashes plus. His curveball is a clear fourth pitch and he should throw it less or shelve it in favor of the other weapons. He really looks like a No. 3 starter, just lacking the track record beyond a single year of starting in Low A.
It’s interesting to see the difference in evaluation on the curveball — for Law and MLB.com, it’s Prosecky’s weakest pitch but for Longenhagen, it’s his best.
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, though 2024 was more of a sideways step than a forward one due somewhat to the elbow injury. His stuff misses bats, but not enough that his run prevention numbers looked strong in High-A.
I anticipate he’ll be back in Spokane to begin this season (which is his 40-man roster evaluation year), with a mid-season move to Hartford in the offing to test him against upper minors hitting (and show the Rockies if he’s worth protecting from the Rule 5 draft). I ranked Prosecky at the top of my 40 FV tier, 19th on my list.