Williams had another productive season in 1925, hitting .331 with 25 home runs and 105 runs batted in, and led the league with a .613 slugging percentage. Williams continued to hit well for the remainder of his career with St. Louis until December 15, 1927, when he was purchased by the Boston Red Sox for $10,000. He played two more seasons for the Red Sox, hitting for a .345 average in 1929 at the age of 39. Williams returned to the minor leagues in to play two more seasons for the Portland Beavers before retiring in at the age of 41.