Relief Pitching: The Key to MLB Success?
With the MLB trade deadline approaching, the need to strengthen the bullpen becomes paramount for contending teams aiming for glory in October. The 2025 season was no exception, with several strategic moves seeking to consolidate the final part of the games. The New York Yankees were one of the most active teams, adding a trio of relievers: David Bednar from the Pittsburgh Pirates, Camilo Doval from the San Francisco Giants and Jake Bird from the Colorado Rockies. These reinforcements joined a bullpen that had recorded a worrying 4.89 ERA in the previous two months. The debut of these relievers last Friday resulted in an unfortunate encounter against the Miami Marlins. Despite an initial 6-0 lead, which extended to 9-4, the Marlins scored six runs in the bottom of the seventh inning, sealing the Yankees’ 13-12 defeat. The new bullpen members allowed a total of nine runs, with Doval wasting the opportunity to save the game by conceding three runs in the ninth inning, including an error by Jose Caballero, also acquired at the trade deadline. The Yankees weren’t the only ones to reinforce their bullpen. The New York Mets traded for Ryan Helsley, Tyler Rogers, and Gregory Soto. The Detroit Tigers acquired Kyle Finnegan, Rafael Montero, and Paul Sewald. The Chicago Cubs added Andrew Kittredge, Taylor Rogers, and Michael Soroka. In addition, important moves were made, such as the arrival of Jhoan Duran to the Philadelphia Phillies, and the acquisition of Mason Miller by the San Diego Padres. The key question is: How much does reinforcing the bullpen really help at the deadline? Relievers can be unpredictable. They could pitch only 20 innings in the remainder of the regular season, and a couple of bad performances at crucial moments can negate the impact of several good outings. These decisions not only seek to secure a place in the postseason, but also to win once there, as bullpens are used more frequently in the playoffs than in the regular season. In the last four postseasons, relievers accumulated 50% of the innings pitched. Last year, this figure was close to 52%, compared to 41.2% in the regular season. The Los Angeles Dodgers, with a rotation affected by injuries, relied heavily on their bullpen, which accounted for 58% of the team’s innings in the playoffs, on their way to the World Series title. Each team would seek to replicate the success of the Houston Astros in 2022, when their bullpen dominated the postseason with an ERA of 0.83.Next, we analyze the performance of teams that invested in relievers or acquired elite closers in the past, to assess whether these strategies have paid off.
Analysis of Past Movements
2024 Padres
Additions: “Tanner Scott, Jason Adam, Bryan Hoeing” ERA of the bullpen: Until July 31: 4.07 | After July 31: 3.19 Team record: Through July 31: 59-51 (.537) | After July 31: 34-18 (.654) The Padres acquired Scott and Adam, significantly reinforcing their bullpen. Although they had already begun to improve, winning nine out of every ten games before July 31, and then ten out of twelve immediately after the deadline, they managed to go from a close wild card competition to comfortably leading, with an improved bullpen. Although the Dodgers won the National League West Division, the Padres showed that a great bullpen is not enough if runs are not scored.2024 Mets
Additions: “Phil Maton, Ryne Stanek, Huascar Brazoban” ERA from the bullpen: Until July 31: 4.05 | After July 31: 3.99 Team Record: Through July 31: 57-51 (.528) | After July 31: 32-22 (.593) Like the Padres, the Mets improved in the last two months after the deadline, although it wasn’t precisely because of the bullpen additions. Maton was the only one of the three to have an impact, with a 2.51 ERA in 31 appearances. However, he struggled in the postseason, and although the Mets reached the National League Championship Series, the bullpen had a 5.56 ERA in the playoffs, including 6.75 in the Championship Series.2023 Texas RangersAdditions: “Aroldis Chapman, Chris Stratton” ERA of the bullpen: Until July 31: 4.83 | After July 31: 4.67 Team Record: Through July 31: 60-46 (.566) | After July 31: 26-23 (.531) The Rangers had a poor bullpen all year, and although Chapman had six holds in the playoffs, the closer in the World Series was Josh Sborz, who had a 5.50 ERA in the regular season. However, he performed well at the right time, allowing only one run in 12 postseason innings.2022 Padres
Addition: Josh HaderERA of the bullpen: Until July 31: 3.94 | After July 31: 3.47 Team Record: Through July 31: 57-46 (.554) | After July 31: 31-27 (.534) The Padres acquired Hader and Juan Soto, but they didn’t improve in the final stretch. Hader had an ERA of 7.31 in 19 appearances, losing two of his nine save opportunities. Although they beat the Mets and the Dodgers in the playoffs, they lost to the Phillies in the National League Championship Series.2021 Astros
Additions: “Kendall Graveman, Phil Maton, Yimi Garcia, Rafael Montero” ERA of the bullpen: Until July 31: 4.08 | After July 31: 3.89 Team Record: Through July 31: 64-41 (.610) | After July 31: 31-26 (.544) Graveman was the key acquisition, but he didn’t perform the same in Houston. The Astros reached the World Series, where they lost to the Braves.2021 Toronto Blue Jays
Additions: “Adam Cimber, Trevor Richards, Brad Hand, Joakim Soria” ERA of the bullpen: Until July 31: 4.01 | After July 31: 4.21 Team Record: Through July 31: 53-48 (.525) | After July 31: 38-23 (.623) The Blue Jays improved after the deadline, but Cimber was the only acquisition with impact. Although they won 12 of 13 games in September, they failed to reach the playoffs.2019 Atlanta BravesAdditions: “Shane Greene, Mark Melancon, Chris Martin” ERA of the bullpen: Until July 31: 4.14 | After July 31: 4.26 Team Record: Through July 31: 64-45 (.587) | After July 31: 33-22 (.600) The Braves added good relievers, but lost to the Cardinals in the National League Championship Series.2019 Cubs
Additions: “Craig Kimbrel, Derek Holland, David Phelps, Brad Wieck” ERA of the bullpen: Until July 31: 4.17 | After July 31: 3.65 Team Record: Through July 31: 57-50 (.533) | After July 31: 27-28 (.491) Kimbrel did not perform well, and the Cubs collapsed in September, missing the playoffs.2019 Washington NationalsAdditions: “Daniel Hudson, Fernando Rodney, Hunter Strickland, Roenis Elias” ERA of the bullpen: Until July 31: 5.96 | After July 31: 5.11 Team Record: Through July 31: 57-51 (.528) | After July 31: 36-18 (.667) Although the bullpen didn’t improve significantly, the Nationals won the World Series, with Hudson being key.2018 AstrosAdditions: Roberto Osuna, Ryan PresslyERA of the bullpen: Until July 31: 3.18 | After July 31: 2.77 Team Record: Through July 31: 68-41 (.624) | After July 31: 35-18 (.660) The Astros won 103 games, but lost to the Red Sox in the American League Championship Series.2018 Arizona DiamondbacksAdditions: “Brad Ziegler, Jake Diekman, Matt Andriese” ERA of the bullpen: Until July 31: 3.03 | After July 31: 4.63 Team Record: Through July 31: 60-49 (.550) | After July 31: 22-31 (.415) The Diamondbacks, who led the National League West, added bullpen help, but the team collapsed and didn’t make the playoffs.
