Can loading up on relievers at the deadline win you a World Series? We found out

Relief pitchers tend to be a need for teams around MLB's trade deadline as contenders gear up to make an October run -- and 2025 was no different. The New York Yankees added a trio of relievers in David Bednar from the Pittsburgh Pirates, Camilo Doval from the San Francisco Giants and Jake Bird from the Colorado Rockies to help a bullpen that had posted a 4.89 ERA over the previous two months.

The three relievers debuted last Friday -- and delivered a disaster of "Cutthroat Island" proportions against the Miami Marlins. The Yankees were up 6-0 early and then 9-4 heading into the bottom of the seventh inning -- in which the Marlins scored six runs -- and New York eventually lost 13-12. The newcomers combined to allow nine runs, with Doval blowing the save when he allowed three runs in the bottom of the ninth (with the help of an error from Jose Caballero, also a trade deadline acquisition).

The Yankees weren't the only team to load up on relievers. 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 picked up Andrew Kittredge, Taylor Rogers and swingman Michael Soroka. And, of course, there were the blockbuster deals for two of the best closers in the game with the Philadelphia Phillies acquiring Jhoan Duran (as well as signing free agent David Robertson) and the San Diego Padres trading for Mason Miller.

The question then: How much does loading up on relievers at the deadline help? Relievers, after all, can be extremely volatile. They might pitch just 20 innings the rest of the regular season, and it only takes a couple of bad outings in high-leverage moments -- see Bird's initial results with the Yankees -- to nullify a bunch of good outings.

These moves are not just about getting to the postseason, but also winning once you're there, as bullpens are used more often in the playoffs than in the regular season. Over the past four postseasons, relievers accounted for 50% of all innings. Last year, it was nearly 52%, compared with 41.2% in the regular season. The Los Angeles Dodgers, with an injury-riddled rotation last year, relied heavily on their bullpen, the relievers accounting for 58% of the team's playoff innings en route to a World Series title. And every team would love to replicate what the Houston Astros did in winning the World Series in 2022 when their bullpen dominated the postseason with a 0.83 ERA.

We went back to 2018 to see how teams that loaded up on relievers, as the Yankees and Mets did, or added an elite closer, as the Phillies and Padres did, have performed. Have such moves paid off? Let's find out.

2024 Padres

Added: Tanner Scott, Jason Adam, Bryan Hoeing

Bullpen ERA: Through July 31: 4.07 | After July 31: 3.19
Team W-L record: Through July 31: 59-51 (.537) | After July 31: 34-18 (.654)

The Padres acquired Scott, the player every club wanted, plus Adam, maybe the second-best reliever to change teams. They had already started to surge, winning nine of 10 games through July 31, and then 10 of 12 immediately after the deadline, going from a crowded wild-card race to comfortably leading the pack with a much-improved bullpen the rest of the season. Though the Dodgers still won the NL West, the teams met in the NLDS, and the Padres took the series lead only to get shut out in the final two games, making it clear that a great bullpen won't matter if you can't score runs.

2024 Mets

Added: Phil Maton, Ryne Stanek, Huascar Brazoban

Bullpen ERA: Through July 31: 4.05 | After July 31: 3.99
Team W-L record: Through July 31: 57-51 (.528) | After July 31: 32-22 (.593)

Like the Padres, the Mets played better the final two months after the deadline -- although it wasn't really because of the bullpen additions. Maton was the only one of the three to make an impact, posting a 2.51 ERA in 31 appearances. He hit the wall in the postseason, however, and though the Mets reached the NL Championship Series, the bullpen had a 5.56 ERA in the playoffs, including 6.75 in the NLCS.

2023 Texas Rangers

Additions: Aroldis Chapman, Chris Stratton

Bullpen ERA: Through July 31: 4.83 | After July 31: 4.67
Team W-L record: Through July 31: 60-46 (.566) | After July 31: 26-23 (.531)

There isn't really a team that qualifies as "loading up" on relievers in 2023, but let's use the Rangers to illustrate a point. They had a bad bullpen through July (27th in the majors in ERA) and a bad bullpen after July (23rd). Their closer for most of the year had been Will Smith, but Jose Leclerc was closing by October. Chapman had six holds in the playoffs, but the reliever who closed out the World Series was Josh Sborz, who had a 5.50 ERA in the regular season. He got hot at the right time, however, and allowed just one run in 12 postseason innings. Certainly, getting more good relievers improves your odds of success, but any bullpen can get hot for a month.

2022 Padres

Addition: Josh Hader

Bullpen ERA: Through July 31: 3.94 | After July 31: 3.47
Team W-L record: Through July 31: 57-46 (.554) | After July 31: 31-27 (.534)

The Padres acquired Hader and Juan Soto at the deadline, but they weren't any better the rest of the way (actually, considering the deadline that year was Aug. 2, the Padres were just 31-30 with both Hader and Soto). Hader had a 7.31 ERA in 19 appearances with the Padres, blowing two of his nine save chances and losing another game. They beat the Mets and Dodgers in the playoffs to reach the NLCS but lost to the Phillies in five games. The Padres led 3-2 in the eighth inning of Game 5 when Bryce Harper hit the series-winning two-run home run -- off Robert Suarez. Hader pitched only one inning in the series.

2021 Astros

Additions: Kendall Graveman, Phil Maton, Yimi Garcia, Rafael Montero

Bullpen ERA: Through July 31: 4.08 | After July 31: 3.89
Team W-L record: Through July 31: 64-41 (.610) | After July 31: 31-26 (.544)

Graveman was the big acquisition, as he had an 0.82 ERA with the Seattle Mariners. He wasn't as good with Houston (3.13 ERA), although he had a strong postseason with two runs in 11 innings as the Astros reached the World Series (losing to the Braves in six games). The offense was the main reason for the World Series loss, twice getting shut out -- in part due to a mediocre Atlanta bullpen getting hot at the right time, similar to the Rangers two years later.

2021 Toronto Blue Jays

Additions: Adam Cimber, Trevor Richards, Brad Hand, Joakim Soria

Bullpen ERA: Through July 31: 4.01 | After July 31: 4.21
Team W-L record: Through July 31: 53-48 (.525) | After July 31: 38-23 (.623)

The Blue Jays played much better after the deadline, but Cimber was the only impact acquisition, posting a 1.69 ERA in 39 appearances. Hand went 0-2 with a 7.27 ERA in 11 games and was put on waivers, and Soria pitched in just 10 games, allowing seven runs in eight innings. Though the Blue Jays won 12 out of 13 to begin September, they ended up missing the playoffs by one win -- going 3-9 in extra-inning games along the way.

2019 Atlanta Braves

Additions: Shane Greene, Mark Melancon, Chris Martin

Bullpen ERA: Through July 31: 4.14 | After July 31: 4.26
Team W-L record: Through July 31: 64-45 (.587) | After July 31: 33-22 (.600)

The Braves picked up three pretty good relievers here. Greene had 1.18 ERA with the Tigers and was an All-Star. Melancon had a 3.50 ERA with the Giants, and Martin had a 3.08 ERA with the Rangers (those were solid ERAs in 2019 -- the year of the juiced ball). Greene saw his ERA climb to over 4.00 with the Braves, while Melancon took over as the closer and went 11-for-11 in save chances. The Braves lost to the St. Louis Cardinals in five games in the NLDS, with Melancon allowing four runs in the ninth inning to lose Game 1 and Greene blowing a lead in the eighth inning of Game 4 (with starter Julio Teheran getting the loss in the 10th inning).

2019 Cubs

Additions: Craig Kimbrel, Derek Holland, David Phelps, Brad Wieck

Bullpen ERA: Through July 31: 4.17 | After July 31: 3.65
Team W-L record: Through July 31: 57-50 (.533) | After July 31: 27-28 (.491)

Kimbrel was a late free agent signing, but we'll include him as he made his season debut in late June. He wasn't good, going 0-4 with a 6.53 ERA, and the Cubs collapsed late in September with a nine-game losing streak and missed the playoffs. That was mostly due to the offense, but Kimbrel lost two games down the stretch while Phelps and Wieck each lost one.

2019 Washington Nationals

Additions: Daniel Hudson, Fernando Rodney, Hunter Strickland, Roenis Elias

Bullpen ERA: Through July 31: 5.96 | After July 31: 5.11

Team W-L record: Through July 31: 57-51 (.528) | After July 31: 36-18 (.667)

This barely qualifies as loading up, as Strickland and Elias were low-impact acquisitions while Rodney was signed as a free agent after the A's released him. Indeed, in retrospect, it's hard to believe the Nationals didn't do more to fortify a bullpen that had the worst ERA in the majors as of July 31 and wasn't much better the rest of the way. It didn't matter though. Hudson pitched great (3-0, 1.44 ERA, six saves) and was the only reliable reliever along with Sean Doolittle, but manager Dave Martinez used starters Stephen Strasburg, Max Scherzer and Patrick Corbin at various times in relief in the postseason, and the Nationals won the World Series -- with Hudson closing it out.

2018 Astros

Additions: Roberto Osuna, Ryan Pressly

Bullpen ERA: Through July 31: 3.18 | After July 31: 2.77
Team W-L record: Through July 31: 68-41 (.624) | After July 31: 35-18 (.660)

The Astros had the third-best bullpen ERA at the trade deadline but made two deals anyway. Osuna was a controversial acquisition because he was just finishing a 75-game suspension for violating the league's domestic violence policy. Ken Giles and Hector Rondon shared closer duties, but Giles (who went to Toronto in the Osuna deal) had struggled the previous postseason and Rondon was a little shaky. Osuna became the closer, and Pressly posted an 0.77 ERA the rest of the way. The Astros won 103 games but lost to the 108-win Red Sox in the ALCS.

2018 Arizona Diamondbacks

Additions: Brad Ziegler, Jake Diekman, Matt Andriese

Bullpen ERA: Through July 31: 3.03 | After July 31: 4.63
Team W-L record: Through July 31: 60-49 (.550) | After July 31: 22-31 (.415)

The Diamondbacks led the NL West by a half-game over the Dodgers and Rockies on July 31 -- thanks in part to owning the second-best bullpen ERA in the majors. Leading the way were Andrew Chafin (1.67 ERA), T.J. McFarland (1.72), Yoshihisa Hirano (2.33), Archie Bradley (3.02) and closer Brad Boxberger (3.49, 25 saves). Perhaps sensing this group was over its head, the Diamondbacks added help -- but the bullpen collapsed anyway. Ziegler, Diekman and Andriese went 1-5 with a 6.55 ERA, while the others all saw their ERAs rise. Arizona finished 82-80 and missed the playoffs.

So, are there any takeaways?

Bottom line: Bullpens are forever unpredictable, which means anything can happen over the next two months for the teams that hoped to make upgrades. Bullpens are even more unpredictable in October, when the limited number of games and extra days off means any pen can get hot -- see Atlanta in 2021 and Texas in 2023 -- and even great relievers can have a couple of bad games that might cost a team a playoff series. And if your offense doesn't score runs, your top relievers won't get to close out leads anyway.

It's all about improving your odds, adding depth and giving your manager more options (and not wearing down your best relievers down the stretch).

The Padres already had the lowest bullpen ERA in the majors this season before adding Miller and seem like a club that could pull off a 2022 Astros-like run to a World Series title (a team that had the best bullpen in the regular season). The Mets added a strong group of setup men in front of ace closer Edwin Diaz, turning a potential weakness into what looks like a strength. The Tigers' pen ranks 19th in ERA and 28th in strikeout rate. We'll see if their additions can make an impact. The Phillies might finally have the lights-out closer they've needed in Duran, and maybe he can close out playoff games, which Craig Kimbrel and Jeff Hoffman failed to do the past two postseasons. The Milwaukee Brewers didn't make any significant additions and rank just in the middle of the pack in bullpen ERA, but their high-leverage relievers -- Trevor Megill, Abner Uribe, Nick Mears, Aaron Ashby -- have been excellent. We'll see if that's enough.

And the Yankees? The bullpen looks good on paper -- and, hey, it could get hot at the right time in the playoffs. If the Yankees even get in.