The underrated relief prospect who is dominating minor leaguers in the Pittsburgh Pirates’ system

When talking about the Pittsburgh Pirates’ farm system, it’s easy for a pitcher to get overshadowed. Bubba Chandler, Thomas Harrington, Hunter Barco, Braxton Ashcraft, and about a half-dozen other pitching prospects have all gotten a ton of attention this year. But one who has seemingly flown under the radar is left-hander Luis Peralta. It’s easy to overlook a relief pitching prospect, as most relievers were once starters, but Peralta deserves more attention. He has dominated the minor leagues like almost no other pitcher has.

Peralta has now pitched 36.2 innings between Greensboro and Altoona, posting an ERA of just 0.49. He is the only minor league reliever with an ERA below 0.50 in at least 30 IP this year. Keep in mind that the lowest single-season ERA from a major league reliever in the game's history is 0.54, as set by Zack Britton in 2016. Peralta also has a FIP of just 1.93 and a WHIP below 1.00 at 0.93. Peralta has struck out over 40% of his opponents, with a 41.3% K%, but has a mediocre 11.9% walk rate. 

Despite allowing walks at a below-average rate, he has yet to allow a home run. Peralta has a 47.6% ground ball rate. His 2.68 xFIP is the lowest among all Pirates minor-league arms with at least 30 frames under their belt. Peralta also has a flyball percentage just north of 30% at 30.2%.

Why isn't anyone noticing record-threatening Pirates relief prospect Luis Peralta?

Peralta has been one of the best relievers in all of minor-league baseball. Among pitchers with at least 30 IP and one or zero games started, Peralta has the best ERA, the seventh-best FIP, fifth-best strikeout rate, and is only one of 50 other relievers who have yet to allow a home run this season. Plus, he’s one of just 43 bullpen pieces with a WHIP below 1.00.

This is a humongous season for Peralta. Of course, that would be true for any pitcher with an ERA under 1.00 at this point of the year, but Peralta looks like a completely different prospect. From his pro debut in 2018 as a 17-year-old through last season, Peralta’s numbers weren’t great. He owned a 4.77 ERA, 4.29 FIP, and 1.49 WHIP. While he carried a healthy 28.8% K% and 0.74 HR/9, he was even more prone to walks than he is now. Peralta’s BB% through his first five pro seasons was 13.5%.

Peralta is starting to get some more attention directed his way. FanGraphs placed him as the Pirates’ 25th-best prospect, projecting him to have two plus offerings and above-average command. Baseball America is even more bullish on him, as they have him as the Bucs’ 20th-best prospect. In their write-up on the lefty, they like his four-seamer, mentioning it has good movement and velocity, and he can throw it for strikes. They also mention that his slider generates plenty of swings and misses, but he can still struggle with command of his secondaries from time to time.

Good left-handed relievers are hard to come by, and the Pirates potentially have one in the minor leagues with Luis Peralta. He’s made some promising steps forward and might find himself as a potential relief option late into this season or, at the very least, next year. Peralta is Rule 5 draft eligible this offseason, so the Pirates must include him on their 40-man roster if they want to protect him from getting selected. He'd almost assuredly get picked up early with how well he’s been pitching and his clear improvements. Because of that, Peralta could be a potential bullpen option for the Pirates in 2025 at the latest.