Rettenmund played halfback at Ball State and was drafted by the Dallas Cowboys. He chose baseball and played in four World Series and six LCS with three different clubs. He was named TSN Minor League Player of the Year in 1968 when he batted .331 with 22 HR for Rochester (International League). He was the AL champion Orioles’ leading hitter in 1970 (.322) and 1971 (.318). In the NL he became a platoon player and top pinch hitter, and he went a league-leading 21-for-67 in the pinch for the 1977 Padres, the eighth most pinch hits ever in a single season.