How Bad Can an MLB Bullpen Be and Still Make October?

[Cody Christie]

Bullpen usage has undergone a quiet but dramatic transformation over the last decade. Not long ago, teams could reasonably expect their starters to cover six or seven innings on most nights, handing the ball to a defined late-inning trio to close things out. That model has steadily eroded. Today’s game asks starters to work fewer times through the order, often exiting before trouble begins rather than after it has already arrived. The result is a growing share of innings being pushed onto bullpens that are asked to do more than ever before.

That shift has fundamentally changed how teams build pitching staffs, and a deep bullpen is no longer a luxury. It is a necessity. Clubs are now tasked with finding eight or more arms capable of navigating high leverage situations, absorbing bulk innings, and bridging the gap created by shorter starts. It is not just about having a closer and a setup man anymore. It is about layering options and maintaining flexibility across a 162-game season.

The challenge is that not every organization approaches bullpen construction the same way. Some franchises can spend aggressively, stockpiling established late-inning arms without worrying about diminishing returns. Others are forced to be more creative, piecing together bullpens through internal development, waiver claims, and minor league deals. For those teams, volatility is part of the equation. Relief performance can fluctuate wildly from year to year, making it one of the hardest areas to stabilize.

That raises an important question. Just how good does a bullpen actually need to be for a team to reach the postseason? Recent history suggests the answer is more flexible than you might expect.

2025 Season

The 2025 season offers a strong example of the lower bound. 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, respectively. None of those groups would be considered strengths, yet all were attached to postseason clubs.

Win probability added tells a similar story with a different twist. The Los Angeles Dodgers had the lowest bullpen WPA among playoff teams at just 0.18, and they still ended the year 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, there was a wide range of effectiveness, and elite results were clearly not a prerequisite.

2024 Season
The 2024 season reinforces that idea while adding a few more wrinkles. The Houston Astros led playoff teams in the wrong direction with a bullpen worth just 2.2 fWAR. They were followed by the Yankees at 2.9, the Royals at 3.5, and both the Orioles and Mets at 3.8. Those are not catastrophic numbers, but they fall firmly in the lower tier of postseason participants.

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 Season
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. Their group finished with just 2.0 fWAR and a -2.55 WPA, both 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, and whatever flaws existed over 162 games became far less relevant in October.

Even teams that were closer to the middle illustrate the broader point. Minnesota finished with a 3.6 fWAR bullpen, while Houston checked in at 4.0. For WPA, the Rays had a 2.31 WPA and the Braves had a 3.05 WPA. The range of outcomes shows just how little correlation there can be once the postseason begins.

Some recent poor performances from playoff bullpens:

Team	WPA	fWAR
Rangers (2023)	-2.55	2.0
Royals (2024)	-1.31	3.5
Dodgers (2025)	0.18	6.0
Padres (2024)	0.19	5.4
Diamondbacks (2023)	0.41	2.2
Orioles (2024)	0.99	3.8

So where does that leave us? The data from the last three seasons suggests that most playoff teams still feature bullpens that land somewhere in the middle of the pack (or higher) by both fWAR and WPA. Truly poor units can sneak in, but they are more the exception than the rule. Over a full season, it is difficult to consistently win while giving away too many innings late in games.

At the same time, October operates under a different set of conditions. Off days allow managers to lean heavily on their best arms, shortening the bullpen and masking depth issues. A team that might struggle to cover nine innings in June can suddenly thrive when it only needs three or four trusted relievers in a playoff series. Get hot at the right time, and even a flawed bullpen can look dominant.

The takeaway is not that bullpens do not matter. It is that they matter differently depending on the context. Over 162 games, competence is usually required. In October, timing can be everything.

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