Batting average against

Sandy Koufax had a .179 batting average against in 1965, the best in Major League Baseball for that season.

In baseball statistics, batting average against (denoted by BAA or AVG), also known as 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.