The Pittsburgh Pirates built a bullpen of afterthoughts, and it’s working tremendously

After being arguably the most disappointing part of the 2024 season, the Pittsburgh Pirates’ bullpen has been one of their biggest strengths for most of this year. Since the start of May, Pirates’ relievers have a 3.53 ERA, 3.47 FIP, and 1.18 WHIP. While they’ve only struck out 21.4% of the opponents they've faced, they have an 8.9% walk rate and the game's lowest HR/9 at 0.60. Not only has the output been fantastic, but some of their best-performing arms were mostly afterthoughts when the Pirates acquired them.

The most prominent example is Dennis Santana. The Bucs acquired Santana last June, claiming him off waivers from the New York Yankees. Although Santana once ranked as a top 10 prospect in the LA Dodgers’ usually deep farm system, he had bounced around between the Dodgers, Rangers, and both New York teams before landing in Pittsburgh.

Santana had a phenomenal year with the Pirates in 2024, and looks excellent once again this season. Santana has tossed 37 innings, working to a 1.36 ERA, 2.50 FIP, and 0.78 WHIP. While Santana’s K% has fallen to just 20.3%, his walk rate of 5.1% is the 16th-lowest among all relievers this season. The right-hander has allowed just a single home run, and has both an 87.7 MPH exit velocity (85th percentile) and a 6.7% barrel percentage (71st percentile). Despite the low K%, he still has an above-average 35% chase rate, which sits in the 96th percentile, along with a 60th percentile whiff rate at 26.3%.

Pirates' bullpen made up of incredible afterthoughts, like Dennis Santana and Chase Shugart

Chase Shugart has been another quality find by the Bucs. All the Pirates had to surrender was their 13th-round pick, Matt McShane, to the Boston Red Sox to acquire him. Although McShane is doing well, he’s still only at High-A, and the Pirates are likely happy with how well Shugart has done. The right-hander has a 2.97 ERA and 1.13 WHIP across 36.1 innings. There are definitely some red flags to his game. He has only struck out 14.3% of opponents with an unimpressive 10.2% walk rate. xFIP and SIERA say he’s way overperforming - at 5.09 and 5.27, respectively. 

However, Shugart can overperform some of these metrics if he continues to induce soft contact at the rate he has. The right-hander has just an 86.7 MPH exit velocity, which is in the 93rd percentile of all pitchers. His 7.3% barrel percentage is also above-average in the 64th percentile. While Shugart has a .208 batting average on balls in play, he is a flyball pitcher who induces weak contact. He should be expected to put up a lower-than-average BABIP. It also helps that he has good stuff and has a 104 Stuff+ rating.

Although he has far fewer innings pitched than either Santana or Shugart, Isaac Mattson has also been a very fun story to watch. A Pitt alumni, Mattson was a 19th-round pick by the LA Angels, and toiled around in the minor leagues. After getting traded to the Baltimore Orioles in the Dylan Bundy swap, Mattson made his MLB debut in 2021, but only appeared in four games. Mattson then took his talents back to PA, pitching for the Frontier League Washington Wild Things in 2022. After spending part of 2023 in the Minnesota Twins’ system, Mattson signed with the Pirates for 2024 and is now a key part of their bullpen.

Mattson has only tossed 16.2 innings, but has allowed just a trio of earned runs. Although he’s allowed two home runs, he’s also struck out 17 with only a half-dozen walks. Mattson is inducing plenty of weak contact, with a microscopic 2.6% barrel rate throughout this small sample size. He has become one of the Pirates’ most valuable relievers. Since making his season debut on May 22nd, Mattson’s +0.78 win percentage added is the third highest among Pirates’ relievers, only behind Santana and closer David Bednar.

If there’s at least one thing the Pirates are doing right, it’s finding good pitchers, especially relievers. Finding diamonds in the rough like Santana, Shugart, and Mattson have significantly helped out the bullpen. It would be hard to imagine where the Pirates’ pen would be right now if they hadn’t found these three arms. They’ve all been key hurlers for the Bucs this season.