Born in Chicago, Masi attended Austin High School, then began his professional baseball career when he was contracted in by the Cleveland Indians at the age of 20. In he played for the Wausau Timberjacks and demonstrated his versatility by playing as a catcher, outfielder, third baseman and as a first baseman. Masi became known as the Pepper Martin of the Northern League because of his head-first slides and prancing running style, while leading the league with 31 home runs and being named to the league's All-Star team.