 Mahan played in the Boston Red Sox organization from 1936 until he was sold to the Phillies in April 1940.He played one season for the Phillies, and posted a .244 batting average (133-for-544) with two home runs and 39 RBI in 146 games played, including 55 runs, 24 doubles and five triples.He hit a double off the wall his first time at bat and led the Phillies in stolen bases.