The Dominican left-hander was signed by the Rockies in 2022, and had an electric 2024 season
30. Luichi Casilla (75 points, 12 ballots)
Casilla was a pop-up arm in 2024 for scouts after signing for $160k back in 2022. The 6’2”, 180-pound Dominican lefty was electric in a seven-start season in 2022 (1.19 ERA, 11.1 K/9 rate, 22 2⁄3 innings) in the Dominican Summer League, then got more playing time in 2023 in the DSL. That year, he threw 40 2⁄3 innings in 11 games with a 3.32 ERA, 1.40 WHIP, 9.7 K/9 rate, and 3.8 BB/9 rate.
Casilla was moved stateside in 2024 to the Arizona Complex League, where he was 2.1 years younger than league average. His run prevention numbers weren’t great — he had a 7.00 ERA, 1.72 WHIP, and 7.0 BB/9 rate in 36 innings across 12 games — but he did strike out 57 hitters in those 36 innings (14.3 K/9 rate) and his 4.49 xFIP indicated some poor fortune in those results.
Here’s some video of Casilla from last spring courtesy of Fangraphs (and here’s some more recent footage from the ACL albeit from a side angle):
That performance wasn’t necessarily the catalyst for his rise into Purple Row’s prospect consciousness. Rather, it was Eric Longenhagen’s glowing scouting report from spring 2024 at Fangraphs, categorizing him as a 40+ FV prospect. Longenhagen backed off that a bit in his recent system update, but still ranked Casilla as a 40 FV prospect, 31st in the system, with plus projection on both his upper 90s fastball and curveball:
A high-waisted, bubble-butted southpaw with a rectangular frame, Casilla was one of the more exciting pop-up arms of early 2024 backfield action, as the teenage lefty’s fastball was routinely in the 95-98 mph range, and he flashed a nasty two-planed breaking ball. Frustratingly hittable and wild, he posted a 32.9% K% and 16.2% BB% in 12 regular season appearances, then Casilla seemed to get hurt during Instructional League activity toward the end of September. The exact severity of the injury is unclear, but it looked pretty bad. His fastball angle and shape cause it to play beneath its velocity, his command dilutes the effectiveness of his entire repertoire, and he needs to develop a third pitch in order to start, but Casilla’s arm strength and breaking ball quality are a great starting point for a young pitcher. If his injury was bad enough to cost him a portion of 2025, it will funnel him further toward a reliever future, though he has late-inning upside in that role.
We’ll don’t know how that injury will affect Casilla’s availability for 2025, but if he’s healthy he’ll probably spend the year at Low-A Fresno. I’m enough of a believer in the potential to rank Casilla as a 40 FV player and the last player left off my list, though it’ll be a while before we see what amount of that potential is realized.