FIP (Fielding Independent Pitching)

Pitchers only control three things: Strikeouts, Walks (and HBP), and Home Runs. Everything else involves the defense.

FIP scales these three outcomes to look like ERA, so a 3.00 FIP is excellent, while a 5.00 FIP is poor. If a pitcher has a 3.00 ERA but a 4.50 FIP, he is likely getting lucky with defense or sequencing, and regression is imminent.