Batting average against
In baseball statistics, batting average against (denoted by BAA or AVG), or opponents' batting average (denoted by OBA) is a statistic that measures a pitcher's ability to prevent hits during official at bats. It can alternatively be described as the league's hitters' combined batting average against the pitcher. It is calculated as: Hits Allowed divided by (Batters Faced minus Walks minus Hit Batsmen minus Sacrifice Hits minus Sacrifice Flies minus Catcher's Interference).
It is calculated as: