How Bad Can An MLB Bullpen Be & Still Make October?

Bullpens matter more than ever, but not always in the way you would expect. Starters are working fewer innings, which means relievers are covering a larger share of the game and often stepping into higher-leverage spots earlier. That should make bullpen quality a defining trait for contenders, and in some cases, it is. But when you start looking at recent playoff teams, the line between a strength and a weakness gets blurry pretty quickly.

So, how bad can a bullpen actually be and still reach October? The answer is lower than most would guess. In recent seasons, several playoff teams have reached the postseason with relief groups that ranked near the bottom in key metrics. While not the common path, these cases show a flawed bullpen does not necessarily sink a season if the rest of the roster compensates.

2025 MLB Bullpens

The 2025 season provides a clear case in point regarding these lower limits. Among playoff teams, the Detroit Tigers posted the worst bullpen fWAR at 1.4. That number stands out even more when compared to the next closest team, as the New York Yankees more than doubled it with a 2.8 mark. Philadelphia and Toronto also found themselves near the bottom, finishing at 2.9 and 3.2 fWAR, respectively.

To better understand the bullpen's impact, win probability can more accurately gauge high-leverage performance. The Los Angeles Dodgers had the lowest bullpen WPA among playoff teams at just 0.18, yet still finished as World Series champions. The Yankees again appeared near the bottom at 1.96, followed by Philadelphia at 2.54 and Cincinnati at 3.37. Even among contenders, effectiveness varied widely, showing that elite results were not essential.

It is also worth noting how much easier it is to reshape a bullpen at the trade deadline. Philadelphia paid a steep price, sending multiple top-100 prospects to Minnesota for Jhoan Duran, while the Yankees swung a four-player deal with Pittsburgh to bring in David Bednar. Contending teams know relief help is one of the most direct ways to patch a weakness, and they are often willing to pay for it.

2024 MLB Bullpens

The 2024 season reiterates these themes. The Houston Astros led playoff teams in the wrong direction with a bullpen worth just 2.2 fWAR. Next were the Yankees at 2.9, the Royals at 3.5, and both the Orioles and Mets at 3.8. While not catastrophic, these numbers rank among the lower tiers among postseason teams.

Looking at WPA, the Royals stand out even more. They were the only playoff team with a negative bullpen WPA at -1.31, meaning their relief corps actively cost them more than a win over the course of the season. San Diego hovered just above water at 0.19, while Baltimore and New York both finished just under one. Again, these are not dominant units. They are survivable ones.

2023 MLB Bullpens

Then there is 2023, the season that breaks the model. The Texas Rangers rode one of the weakest bullpens in the playoff field all the way to a championship, with just 2.0 fWAR and a -2.55 WPA—the lowest marks among postseason teams. Arizona was not far behind, ranking second worst in both categories with a 2.2 fWAR and a 0.41 WPA. Both teams caught fire at the right time, making bullpen flaws less relevant in October.

Teams that were closer to league average still illustrate the broader point. Minnesota finished with a 3.6 fWAR bullpen, while Houston checked in at 4.0. For WPA, the Rays posted 2.31, and the Braves had 3.05. The range of outcomes further highlights how little predictable correlation exists once the postseason begins.

Some recent poor performances from playoff bullpens:

Overall, recent seasons show that most playoff teams still feature at least a competent bullpen, with only a handful succeeding with significantly below-average relief units. While truly poor bullpens can sneak into the postseason, it remains uncommon to win consistently while struggling late in games.

At the same time, October operates differently. Off days allow managers to use their best arms more often, reducing bullpen reliance. A team that struggles to cover nine innings in June can thrive with just three or four trusted relievers in a playoff series. When a bullpen gets hot at the right moment, even its weaknesses become less apparent.

The key takeaway is that bullpens are important, but their significance varies depending on the situation. Throughout the long regular season, reliable bullpen performance is usually necessary to sustain success. However, in October, the impact of timely performances and managerial decisions becomes much greater, allowing even teams with historically average or weak bullpens to thrive. Context and timing are crucial when evaluating the true impact of a bullpen.