xFIP
Expected FIP — like FIP but normalizes HR/FB to league average to remove HR luck.
What xFIP means
Useful for predicting next-year ERA, since pitcher HR/FB rates are noisy year-to-year. Closer to "true talent" than ERA or FIP.
What counts as a good xFIP
Lower is better — roughly 4.4 is poor, 4 average, 3.6 good, and 3.2 or better elite.
Also written
xfip_value · expected_fip
Source
FanGraphs