John “Jack” Stonebraker started playing baseball at 8 years of age with a Junior baseball team known as the Oak Hill Eagles, playing six years. He graduated from Choates Prep School, where he lettered in basketball, baseball and football. He attended the University of Maryland, playing football, basketball and baseball and lettering in all three years (freshmen were not eligible to play at the time).

Jack signed with the New York Yankees. The first year, he played with the Amsterdam Class C team and was selected to the All-Star team, with a batting average of .290. He then played with Norfolk in the Piedmont League and later with the Class AA Kansas City team.

Jack then coached the American Legion baseball team for three years and Boys Club baseball and basketball teams for four years. He helped many young boys who later became professional baseball players.