A 5th round election of the Detroit Tigers in the 1978 amateur draft, Castillo began his career as a third baseman but was used at first base and as a catcher in the minor leagues. He debuted with Detroit in 1981 but didn’t really become a fixture on the roster until 1983 when manager Sparky Anderson tagged him as a bench player because of his versatility. In ’84, Castillo saw action in 70 games, playing third in 33, catching in 36, and DHing once. He served as the primary backup to starter Lance Parrish, often catching Detroit’s 4th or 5th starters – Juan Berenguar, Glenn Abbott, or Dave Rozema. He proved especially useful to Sparky over a span of nine days in August when the team played three doubleheaders.
Besides being in the right place to catch the final out of the playoffs, Castillo was valuable in the post-season in other ways. The right-handed batter drove in the the final run of the playoffs against the Kansas City Royals, and in the Fall Classic he hit .333 (3-for-9) with a home run off lefty Tim Lollar in Detroit’s Game Three victory.
After his playing career, Castillo found himself in trouble with the law. In 1999 he was convicted of assault and battery against his wife. Late in 2011 he faced similar charges and as of August of 2012 a trial was pending.