Expected Outcome stats help to remove defense and ballpark from the
equation to express the skill shown at the moment of batted ball
contact. By looking at the exit velocity and launch angle of each
batted ball, a
is assigned based on the outcomes of comparable historic balls in
play. By accumulating the expected outcomes of each batted ball with
actual strikeouts, walks and hit by pitches,
Expected Batting Average (xBA)
Expected Slugging (xSLG)
, and (most importantly)
Expected Weighted On-Base Average (xwOBA)
tell the story of a player's season based on quality of and amount
of contact, not outcomes.
* Qualifiers: 2.1 PA per team game for batters, 1.25 PA per team
game for pitchers.