FIP (Fielding Independent Pitching) is a sabermetric stat that strips defense and luck out of pitcher evaluation. It's more predictive of next-start ERA than raw ERA. Here's how it works and why it matters for betting.
FIP estimates a pitcher's run prevention based ONLY on outcomes the pitcher fully controls: strikeouts, walks, hit-by-pitches, and home runs. Defense + ball-in-play luck are stripped out. The formula:
FIP = ((13 × HR) + (3 × (BB + HBP)) - (2 × K)) / IP + FIP-constant
The FIP-constant (typically ~3.10) calibrates FIP to the same scale as ERA so the two are directly comparable.
ERA includes outcomes the pitcher doesn't fully control — defensive plays, BABIP variance, sequencing luck. A pitcher with a 4.50 ERA but a 3.00 FIP has been UNLUCKY (defense fails them, hits cluster) and is likely to regress positively. The opposite — 3.50 ERA, 4.50 FIP — is a pitcher who got LUCKY and will regress negatively. FIP is much more predictive of next-start ERA than past ERA.
100 = league average, 90 = 10% better than league. Removes both park and league effects, directly comparable across pitchers.Our model uses fipMinus (the park-and-league-adjusted version) when available, blending 85% FIP-based with 15% raw ERA. The SP run-margin coefficient is 0.55 R per 1.0 ERA gap (each starting pitcher throws ~5.5 IP, so 1 ERA × 5.5/9 ≈ 0.61 R). FIP differences between matched starting pitchers are the single biggest driver of MLB game predictions.
When two pitchers' FIP differ by 0.5+ runs, the better one's team becomes a meaningful favorite even if their season ERA is similar.