Weighted on-base average (wOBA) is a single hitting stat that gives different value to walks, singles, doubles, triples, and home runs. xwOBA replaces the actual outcomes with what would have happened on average for batted balls hit at the same exit velocity and launch angle.

Why fantasy managers care: a hitter whose actual wOBA is meaningfully lower than their xwOBA has been hitting the ball just as hard as their stats suggest, but the results haven't followed yet. Bad luck on liners, defensive shifts, ballpark factors. Over a long enough sample, the actual catches up to the expected — that's the buy-low signal.

We surface this on the daily digest's Waiver Wire and OBP Risers sections by flagging hitters whose xwOBA is well above their wOBA. They're the players to add or trade for before their batting average rises.