 Brantley played outfield and designated hitter during parts of four seasons, 1986–1989, all for the Seattle Mariners.As a rookie in , he led the Mariner regulars in hitting with a .302 average, and also had 14 home runs and 54 RBI in 106 games.His only full season as a regular came in when he hit .263 with 15 HR and 56 RBI in 149 games.