After he hit 29 homers for the White Sox in 1950, Zernial was sent to the Athletics in a trade that brought Minnie Miñoso to Chicago in 1951. That year Zernial led the league in home runs (33), runs batted in (129), extra base hits (68), and 17 assists in the outfield. In 1952 he hit 29 homers with 100 RBI, 42 and 108 in 1953.
Zernial was the first major leaguer to hit four home runs in the month of October during the regular season, since 1900, which he accomplished during a doubleheader on October 1, 1950. Ron Kittle would become the second player to do this in 1985.