Here are the top 10 relief pitching prospects

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Every so often, we get questions about relief pitching prospects. We don’t have a specific ranking for them -- there’s no Top 10 RP list like there is for, say, shortstops. Even our recent story picking one future closer for each team has a good amount of current starters we think might be better suited for the bullpen.

That exercise, trying to figure out who will close games in the big leagues, is a bit of a fool’s errand. There are currently 10 Major League closers with eight or more saves this year. Just one, Aroldis Chapman, has been on a Top 100 list (back in 2011).

I’m the first to admit that we don’t do a great job ranking relievers. I don’t know if there’s still a little bit of a “failed starter” mentality with it, and there are a good number of current Minor League relievers who at least entered pro ball as a starter, but a survey of our Top 30 lists showed we have just one pure reliever on a team top 10 (Tucker Musgrove of the Padres). A lot of times guys who are relieving in the Minors have great power stuff but very poor command of it, and that doesn’t come until later.

Not making excuses here, but I want to try to right this reliever wrong. So on the heels of that future closer story, I present you with a more informal top 10 relief pitching prospect list. Before you ask, Musgrove didn’t make it because he’s a former two-way guy who has barely pitched, but hopefully this becomes an annual newsletter tradition.

1. Daniel Espino, RHP, Guardians (No. 16): We all know his long injury history, and his resilience to come back from it. His fastball that still can touch triple digits and his nasty slider are more than enough, and he’s still learning the craft.

2. Alex McFarlane, RHP, Phillies (No. 17): Mostly a reliever in college, McFarlane got some runway to start as a pro, even after coming back from Tommy John surgery. He’s back in the pen, and he’s been lights out, with an ERA under 1.00 and a 12.4 K/9 rate.

3. Ryan Lambert, RHP, Mets (No. 16): Some give Lambert’s heater an 80 grade. It's 95-98 mph with elite ride, and he also has a solid slider. A little refined command could land Lambert in the big leagues.

4. Yilber Díaz, RHP, D-backs (No. 22): He’s touched the big leagues a few times but hasn’t been able to find the zone there. The former starter has three plus pitches (fastball, slider, curve) and was commanding them better in Triple-A this year.

5. Alimber Santa, RHP, Astros (No. 16): This is Santa's second full season as a full-time reliever, and he’s been awfully tough to hit at the upper levels, with a 10.9 K/9 rate and .182 batting average against over the past two seasons.

6. Rolddy Muñoz, RHP, Braves (No. 18): He’s now 26, so the clock is ticketing, and Muñoz's brief big league stints haven’t gone well. But his slider-forward repertoire has been unhittable in Triple-A this year, and he needs another shot.

7. Marco Raya, RHP, Twins (No. 18): The conversion from starter to relief began last year, and it’s still a work in progress. Raya still has a full repertoire, but the fastball-slider combo might be enough as he figures things out.

8. Charlie Beilenson, RHP, Mariners (No. 26): Unlike most on this list, Beilenson isn’t a pure power stuff guy, but he’ll use two fastballs, a kick change and two versions of a slider to befuddle hitters. He’s 26 and looks like he’s mastering Double-A, and he's already a success story as a grad student senior sign.

9. Luis Gastelum, RHP, Cardinals (No. 21): A reliever since he signed out of Mexico for just $30,000 in 2023, Gastelum has reached Triple-A riding a 70-grade changeup that has produced a 46-percent miss rate in 2025-2026 combined, giving some a little bit of a Devin Williams vibe.

10. Craig Yoho, RHP, Brewers (No. 28): Speaking of changeups, Yoho’s is legendary at this point, and no hitter can really touch it. He has a 1.23 career ERA and .162 career BAA in the Minors but has struggled to throw strikes when given opportunities in the big leagues.