17. Welinton Herrera (282 points, 19 ballots)
Herrera is probably the Rockies’ top relief prospect — among pure relievers in PuRPs voting, it was between him and Rule 5 pick RJ Petit (No. 23 PuRP). He’s also the highest ranked of the three players named Herrera in the system to receive votes. The 21-year-old 6’0” Dominican lefty reliever boasts a plus to plus-plus mid-90s fastball coming from an uphill angle and was added to the 40 man roster this off-season. He was a pop-up arm in 2024 in his first taste of full season ball. Herrera, who spent
two years in the DSL after signing in January 2021 for $200k and a season in the ACL in 2023, was a bit wild but showed bat-missing stuff.
Mid-season 2025 Rank: 21
High Ballot: 7
Mode Ballot: 18
Future Value: 40+, set-up reliever
Contract Status: 2021 International Free Agent, Dominican Republic, 40 Man Roster, three options remaining
MLB ETA: 2026
That was enough to get Herrera assigned to Low-A Fresno to start 2024. Herrera, employing a low arm slot from the left side and mid-90s velocity, was immediately dominant. He struck out an absurd 62 hitters (against only nine walks) in just 34 innings (16.4 K/9 rate) with a 2.38 ERA and 1.00 WHIP across 23 appearances at Fresno. Jack Etkin wrote in August 2024 about Herrera’s strong start in Fresno, in case you’d like to read more about his arsenal and Rockies personnel’s quotes about him.
Herrera was promoted to High-A Spokane in late June, where he was 3.1 years younger than league average. Against higher-level opposition, Herrera’s rate stats were less strong (4.76 ERA, 3.75 xFIP, 1.41 WHIP, 9.5 K/9, 4.4 BB/9) in 23 appearances totaling 28 1⁄3 innings, but the fact he was doing it in High-A as a 20-year-old was quite impressive. He was also quite good in the Dominican Winter League (10 IP, 1.80 ERA, 13 K, 6 BB, 7 H) against players who were on average over 10 years older.
In 2025, Herrera went back to Spokane, where he quickly showed he had mastered the level. In 15 appearances and 18 1/3 innings, Herrera collected 10 saves with a sparkly 0.49 ERA, 0.76 WHIP, 14.2 K/9 rate, and 2.9 BB/9 rate. The Rockies promoted him to Double-A Hartford in mid-May, where he was 3.7 years younger than league average. In 37 appearances totaling 46 1/3 innings with Hartford, Herrera added seven more saves with a 3.50 ERA, 1.30 WHIP, 13.6 K/9 rate, and 3.7 BB/9 rate against upper minors hitters. He also represented the Rockies at the prestigious Futures Game in July, where he got the final out to record the save for the NL squad.
Herrera finished his 2025 with a strong stint in the prestigious Arizona Fall League. He pitched in nine games, throwing nine innings while allowing two runs on nine hits and eights walks with 14 strikeouts and one save. In other words, Herrera pitched around a lot of traffic of his own making and was probably fortunate to leave with a 2.00 ERA.
Here’s some video of Herrera courtesy of FanGraphs during fall instructs in 2024:
Herrera was recently ranked 10th in the system by Baseball America and was listed as having the best fastball in the system.
Keith Law of the Athletic ranked Herrera 14th in the system earlier this week:
Herrera’s fastball is 97-100 and he lived off the pitch in High A until the Rockies told him he had to throw his slider more, after which he was a little more balanced and dominated through the rest of the year in Double A. His profile is straight relief, probably the one-inning variety only, but he throws plenty of strikes and it’s a pretty easy delivery for that velocity. He could easily help the Rockies this year.
Eric Longenhagen of FanGraphs ranked Herrera as a 40+ FV player, 13th overall in the system last January, putting a 70 grade on his fastball’s future effectiveness:
A slender, 6-foot tall pure reliever, Herrera spent three years in rookie ball and then exploded in 2024 as he split his season between both A-ball levels, totaling 62.1 innings in 46 games while striking out 92 and allowing just 80 baserunners. His fastball averaged about 94.5 mph during the regular season, but was 95-98 for me during Instructional League and 94-97 in the Dominican Winter League with Aguilas.
Herrera’s drop-and-drive delivery and three-quarters slot combine to create uphill angle on his fastball, making it very tough for hitters to get on top of it when he’s sitting 96-plus; that pitch had an absurd 42% miss rate in 2024. In order to hit his ceiling as a set-up man or closer, Herrera will need to improve at least one of his secondary pitches. His slider was in the 82-84 mph range during the 2024 season and instructs, but has been up in the 86-88 mph range in LIDOM, where it still lacks the finish and depth of a great slider. His changeup, often in the 87-90 mph range, tends to cut on him and finishes in vulnerable locations. Herrera’s long arm swing makes it tough to project a ton on his changeup, but even if his fastball ends up being his only impact offering, it’s going to be good enough for Herrera to be more than just a generic middle reliever. He’s a candidate for quick promotion in 2025 and is likely to be put on the 40-man after the season.
Herrera was ranked 20th in the system by MLB Pipeline last year as a 40 FV prospect with a plus grade on the fastball:
Used only as a reliever, Herrera relies largely on his fastball-slider combination to go right after hitters. His fastball sits around 95 mph and touches 97 and it comes from a low three-quarters arm slot, an upshoot heater that has carry above the barrel that gets a lot of swing-and-miss. He can get too fastball-reliant and will have to keep learning to trust his 84 mph slider. It’s a pitch he has improved by more consistently staying on top of; it flashes better than average while dropping below barrels. He actually has feel for a changeup with depth, but he doesn’t throw it much.
Herrera pounded the strike zone during his time with Fresno, but he wasn’t as sharp with Spokane. He’s made adjustments before, so there’s confidence he’ll be able to become another legitimate big league bullpen piece for the Rockies.
The overall value that can be added by a relief arm is limited, but Herrera certainly seems like a potential late inning reliever (and he’s a lefty to boot), especially given his performance against upper minors hitters in 2025 in Hartford. That performance is why I ranked him 15th on my list at the bottom of my 40+ FV tier. Herrera will probably begin 2026 in the upper minors at either Hartford or Albuquerque, but I expect him to make his big league debut sometime during the season if he remains healthy.
Please keep in mind our Purple Row Community Guidelines when you’re commenting. Thanks!
