When the lights get brighter in October, the margin for error tightens—and nowhere is that margin thinner than in the bullpen.
Last week, we talked tactics in the NCAA 1500m final. This week, we’re shifting gears to baseball, where I asked a seemingly simple question: How much does bullpen strength really matter in the playoffs?
To answer it, I crunched data from every playoff team between 2019 and 2023, tracking their bullpen ERA and FIP alongside how far they advanced in the postseason.
🔎 Bullpens vs. Playoff Performance: What the Data Shows
Let’s start with the big picture: what’s the average bullpen performance by round?
Round
Avg ERA
Avg FIP
Wild Card
3.92
4.09
ALDS
3.81
4.08
NLDS
3.87
4.06
ALCS
3.81
4.08
NLCS
3.70
4.04
World Series
4.02
4.14
Bullpen = all the relief pitchers (non-starters) who come into the game after the starting pitcher. They usually pitch the final innings, often in high-pressure moments. ERA (Earned Run Average) = average number of runs a pitcher allows per 9 innings. Lower is better. FIP (Fielding Independent Pitching) = a stat that measures a pitcher’s performance independent of their team’s defense, focusing on strikeouts, walks, and home runs. It's a way to judge how much of a pitcher's success is under their control. Lower is also better here.
At first glance, there's a clear trend: bullpen ERA tends to improve the deeper you get… until the World Series, when things get weird. Yet, FIP is generally quite steady – perhaps suggesting that ERA (especially come playoff time) is also partially the responsibility of the defense and even some bad luck.
This final jump in ERA though suggests that elite bullpens help you get deep—but once you reach the World Series, all bets are off. Sloppy bullpens (like the 2019 Nationals at a grotesque 5.68 ERA) can still win it all if the bats (and starters) show up.
In fact…
💡 You Don’t Need a Good Bullpen to Win It All
Let’s look at the bullpens of recent World Series champions:
Team
Year
ERA
FIP
Washington Nationals
2019
5.68
4.94
Los Angeles Dodgers
2020
2.74
3.45
Atlanta Braves
2021
3.97
4.04
Houston Astros
2022
2.8
3.45
Texas Rangers
2023
4.77
4.45
A 2.8 ERA? That’s dominant. A 5.68 ERA? That’s almost sabotage. Yet both ended in champagne.
This volatility shows that bullpens are a high-leverage variable, not a prerequisite. A strong pen gives you an edge, but you can also survive chaos—if you’re elite everywhere else. It’s also important to note that the pitching stats here are from the regular season, so it’s important to remember that heating up at the right time is also a recipe for paydirt. So, if you can sneak into the playoffs and your roster is hot at the right time? Well, let’s just say that a well oiled diesel truck is hard to stop.
📈 Year-by-Year Trends
How have playoff bullpens evolved over the past five seasons?
Year
Avg ERA
Avg FIP
2019
4.16
4.18
2020
4.06
4.27
2021
3.8
4.17
2022
3.37
3.68
2023
3.98
4.09
2022 was the bullpen golden year. Elite pens across the board with a playoff-wide 3.37 ERA and 3.68 FIP. That’s lockdown relief pitching at scale.
By contrast, 2019 and 2023 were messier. The average 2023 playoff bullpen allowed a full earned run more per 9 innings than those in 2022. That variance suggests that bullpen reliability is not consistent year-over-year.
🧮 Bullpen Power Index (BPI): Who's Dominated?
To measure sustained bullpen success, I built a Bullpen Power Index (BPI)—a scoring system that rewards teams for strong bullpen performance and deep playoff runs, year over year.
Here’s the leaderboard from 2019–2023 (minimum 3 playoff appearances):
Team
Playoffs
Total BPI
Avg BPI/Yr
Dodgers
5
56.5
11.3
Astros
5
44.5
8.9
Braves
5
44
8.8
Rays
5
43
8.6
Yankees
4
28.5
7.13
Twins
3
26
8.67
L.A.’s bullpen juggernaut is clear—they’ve been the bullpen team of the era. But here’s the punchline:
The Dodgers won just one World Series despite dominating the bullpen landscape.
Meanwhile, the Astros—who’ve had a slightly less dominant bullpen—have been more efficient. Let’s look at that next.
⚖️ Bullpen Efficiency: Who Gets the Most Mileage?
Here I looked at how well each team translated their bullpen success into playoff wins. I calculated this using a custom playoff efficiency metric: playoff success points ÷ bullpen score.
Team
Playoffs
Playoff Score
Bullpen Score
Efficiency
Astros
5
19
25.5
0.75
Blue Jays
3
3
5
0.6
Cardinals
4
6
11.5
0.52
Braves
5
14
30
0.47
Yankees
4
9
19.5
0.46
Brewers
4
5
13.5
0.37
Dodgers
5
14
42.5
0.33
Rays
5
10
33
0.3
Twins
3
5
21
0.24
Efficiency here tells us: How well did they turn bullpen performance into playoff wins? The Astros? Ruthlessly efficient. The Dodgers? The opposite—tons of bullpen firepower, but lackluster return on investment.
🧠 Final Takeaways
Strong bullpens help—but don’t guarantee titles. The 2019 Nationals and 2023 Rangers prove you can overcome shaky pens.
FIP tracks ERA, but not always. Some of the worst ERA bullpens (like the 2019 Nationals) had just-average FIP—suggesting some bad luck or bad defense.
The Dodgers may be over-relying on the bullpen. Their postseason output relative to bullpen quality is low.
The Astros are the most efficient October bullpen team. Their results consistently exceed their raw numbers.
💬 Who's Next?
Are the Orioles building the next great bullpen machine? Can the Phillies break through with their mid-pack FIP? And will anyone dethrone the Astros as the kings of postseason efficiency?
