Expected ERA predicts what a pitcher’s ERA should be based on the quality of contact they allowed, using Statcast data. While FIP looks at strikeouts, walks, and home runs, xERA looks at how hard and at what angle batters hit the ball against this pitcher.

xERA fills a gap that FIP can’t. Two pitchers might have identical FIP (same K, BB, HR rates), but one induces weak contact (lots of grounders and soft fly balls) while the other gets hit hard. xERA captures that difference. The pitcher inducing weak contact will have a better xERA.

The most powerful analysis combines FIP and xERA. A pitcher with a great FIP and great xERA is the real deal — they’re missing bats AND suppressing contact quality. A pitcher with a great FIP but poor xERA might be getting strikeouts but giving up hard contact when batters do connect, which is riskier long-term.

What is a good xERA?

xERA complements the FIP-based NUT Score for pitchers. While NUT uses FIP (strikeouts, walks, HR), xERA considers batted-ball quality. Comparing the two reveals whether a pitcher is suppressing contact quality (good xERA) or just getting strikeouts (good FIP).

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