Armas was prone to injuries and went on the disabled list twelve times during his major league career, missing 302 games.

During spring training in 1977, Armas, Doug Bair, Dave Giusti, Rick Langford, Doc Medich and Mitchell Page were dealt to the Oakland Athletics in exchange for Chris Batton, Phil Garner and Tommy Helms.

In 1982 he set a pair of major league records with eleven putouts and twelve total chances in right field in a single game against the Toronto Blue Jays.

Following the season he was traded, along with Jeff Newman, to the Boston Red Sox for Carney Lansford, Garry Hancock and minor leaguer Jerry King.

Armas was signed as a free agent by the California Angels In July 1987, and played 3 seasons with them (1987–1989) to finish out his Major League career.

Armas is the current Batting coach for the Leones del Caracas a team in the Venezuelan Professional Baseball League.

His 97 career home runs were the Venezuelan professional baseball record, before another center fielder—Robert Pérez "the black wall" of Cardenales de Lara—set a new mark in 2007.