Starting Pitcher ERA vs xERA — Apr 23, 2024
My favorite activity early in the season is to try to capitalize on underperforming and overperforming starting pitchers. I’ll dangle my pitchers with low ERAs whose skills don’t support it and target those who hold high ERAs despite strong skills. In the past, I’ve exclusively used SIERA to identify such pitcher groups. Today, I’ll use Statcast’s xERA, as it utilizes actual batted ball data, so not every ground ball and fly ball are equal, as they are in the SIERA equation. So let’s compare actual ERA to xERA to identify and discuss both the underperformers and overperformers. Don’t forget that any ERA estimator uses actual strikeout and walk rates, so if those metrics seem unsustainable (either on the high or low side), then the expected ERA equation isn’t going to be as helpful.
