Expected batting average uses Statcast tracking data to predict what a hitter’s batting average should be based on how hard they hit the ball and at what angle. Every batted ball gets a hit probability based on its exit velocity and launch angle, and xBA is the average of all those probabilities over a season.

The power of xBA is in the gap between actual BA and xBA. If a hitter has a .220 BA but a .280 xBA, they’re making great contact that isn’t turning into hits yet — probably due to bad luck on batted-ball placement. That’s a buy-low candidate in fantasy. Conversely, a .310 BA with a .250 xBA suggests the hitter is riding unsustainable luck.

xBA has limitations. It doesn’t account for sprint speed (fast runners beat out more grounders), batter handedness, or defensive positioning. But for identifying luck vs. skill in batting average, it’s the best tool available.

What is a good xBA?

xBA feeds into xwOBA, which Baseball Nut uses to calculate xNUT — the expected version of NUT Score. If xBA is higher than actual BA, the hitter is underperforming and due for positive regression.

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