McManus also served as a manager or player-manager with several baseball teams, beginning with the Boston Red Sox in 1932 and 1933. He was also a player-manager of the St. Paul Saints in 1935, the Tulsa Oilers in 1936, the Williamsport Grays in 1938 and 1939, the San Antonio Missions in 1940 and 1941, and the Denver Bears in 1947. He also served as a manager in the All-American Girls Professional Baseball League for the Kenosha Comets in 1944 and the South Bend Blue Sox in 1945 and 1948. In 1951, he led an effort to unionize professional baseball, football, and basketball players under the umbrella of the American Federation of Labor.