​I was already leaning toward writing about this before the Brewers series, but last night’s game really hammered the point home. So, through the lens of my own bullpen rankings, I’ll compare which teams are thriving with a lights-out, effective bullpen and which are bleeding wins because of theirs. In 2026, baseball continues to evolve, and I have a hunch that bullpens are more important than ever. It could turn out that I reveal teams wasting resources on impressive bullpens, or perhaps the best teams will also have the best bullpens; we’ll see. I’m going to tackle this in a somewhat unconventional way, using something I’m calling Correlation Points.
I’m looking at team reliever stats on Fangraphs, pulling in a range of metrics, including rate stats and fWAR. There are 12 teams with a bullpen ERA under 4, and those teams sit at an ERA of 3.8 or lower. The rest of MLB sits above 4.0 ERA. There are 10 bullpens with an ERA in the 4.0–4.5 range. Then we have the least effective bullpens, over 4.50 ERA, with only a handful of MLB bullpens performing at or worse than 5.0 ERA. I’m using a three-tier system: 3 Correlation Points (CP) for tier-1 teams, 1.5 CP for mid-tier teams, and 0.5 CP for the bottom tier. But what about the absolutely elite bullpens? Don’t they matter? Only four MLB bullpens have an ERA under 3.5, so I’ll assign those teams 3.5 CP. It turned out convenient that, under my rating system, the four best bullpens aligned with the four worst bullpens as outliers. Instead of giving any CP to the bottom tier, they’ll receive zero Correlation Points. That’s how I’m treating ERA.
Incorporating xERA is a way to balance out the volatility of ERA. I’ll again assign 3 CP to teams with an xERA under 4.0. There won’t be any bonus points here, since the top-to-bottom spread is tighter. Mid-tier teams with an xERA under 4.40 will receive 2 CP, while the worst bullpens will get 0.5 CP. Then, of course, it’s important to view this through a Fielding Independent Pitching lens, normalizing for how fielding and defense can mask the bullpen’s effectiveness. I’ll apply the same CP logic to FIP: under 4.0 FIP earns 3 CP, middle-range FIP earns 2 CP, and the worst bullpens get 0.5 CP. I’m skipping xFIP because you don’t want to over-adjust for home runs and other factors.
Since a bullpen that can soak up innings while still performing well is valuable, I’ll also use fWAR totals as Correlation Points. The most valuable bullpens by counting WAR will have a meaningful impact on my Correlation Points system, but I don’t want to rely solely on WAR because a winning bullpen isn’t always used heavily. I want to identify teams that have strong bullpens across the board, not just in counting stats.
After I total the Bullpen Correlation Points, I’ll structure everything for SEO and readability, aiming for a thorough analysis of at least 500 words.