Twice an All-Star, Armas played 14 seasons with the Pittsburgh Pirates, Oakland Athletics, Boston Red Sox, and California Angels, compiling a .252 batting average with 251 home runs and 815 runs batted in. Armas started as an outfielder with Pittsburgh in 1976. The following year he was traded to Oakland. In his first three seasons with the Athletics, Armas was on the disabled list many times, and only managed to play 289 games. Armas finally played a full season in 1980, and hit .279 with 35 home runs and 109 RBI in 158 games.