After being one of the Pittsburgh Pirates’ biggest weaknesses in 2024, the bullpen has emerged as a major strength this season. Since the beginning of May, Pirates relievers have posted a 3.53 ERA, 3.47 FIP, and 1.18 WHIP. While their strikeout rate sits at just 21.4%, they’ve limited walks to 8.9% and lead the majors in home runs allowed per nine innings (0.60). Not only have the results been impressive, but several top contributors were largely overlooked when they first joined the organization.
Dennis Santana stands out as the most notable example. The Pirates picked him up off waivers from the Yankees last June. Once a top-10 prospect in the Dodgers’ deep farm system, Santana bounced around with the Dodgers, Rangers, and both New York teams before landing in Pittsburgh.
He had an excellent showing in 2024 and is continuing that form this year. Across 37 innings, Santana owns a 1.36 ERA, 2.50 FIP, and 0.78 WHIP. Though his strikeout rate has dropped to 20.3%, his 5.1% walk rate ranks 16th among all MLB relievers. He’s surrendered just one home run while holding hitters to an average exit velocity of 87.7 MPH (85th percentile) and a 6.7% barrel rate (71st percentile). Despite modest strikeout numbers, he boasts an elite 35% chase rate (96th percentile) and a solid 26.3% whiff rate (60th percentile).
Another unexpected bullpen gem has been Chase Shugart. Acquired from the Red Sox in exchange for 13th-round pick Matt McShane, Shugart has delivered strong results. While McShane is progressing well in High-A, the Pirates are likely pleased with Shugart’s performance: a 2.97 ERA and 1.13 WHIP over 36.1 innings. There are concerns — namely a low 14.3% strikeout rate and a high 10.2% walk rate — and advanced metrics like xFIP (5.09) and SIERA (5.27) suggest overperformance.
Still, Shugart’s ability to induce weak contact may help him continue to defy the numbers. He ranks in the 93rd percentile for exit velocity (86.7 MPH) and is above average in barrel rate (7.3%). His .208 BABIP seems sustainable for a flyball pitcher with such soft contact. Additionally, he possesses a solid 104 Stuff+ score.
Isaac Mattson has also become a pleasant surprise. The former Pitt Panther and 19th-round pick by the Angels had brief MLB exposure in 2021 with Baltimore. After pitching in the Frontier League and a stint with the Twins organization, Mattson signed with the Pirates in 2024 and is now an important part of the bullpen.
Although he’s only thrown 16.2 innings, Mattson has allowed just three earned runs, giving up two homers while striking out 17 and walking six. He’s generated plenty of weak contact, with a barrel rate of just 2.6%. Since debuting this season on May 22, his +0.78 WPA ranks third among Pirates relievers, trailing only Dennis Santana and closer David Bednar.
If there’s one area the Pirates have excelled in, it’s unearthing overlooked pitching talent — particularly in the bullpen. Unearthing arms like Santana, Shugart, and Mattson has paid off in a big way. It’s hard to imagine where the Pirates’ relief corps would be without them. All three have become crucial to the team’s success in 2025.
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