Mitchell coached the Crimson for twelve seasons over three tenures (1916, 1926, 1929–1938), with his record being 216–134. Harvard joined the Eastern Intercollegiate Baseball League for the 1933 season, and he would lead them to their first ever regular season title with a 8–4 record in 1936 that tied for first with Dartmouth.
Mitchell directed the Crimson team for twelve seasons across three tenures (1916, 1926, 1929–1938), resulting in a win-loss ratio of 216-134. In 1933, Harvard entered the Eastern Intercollegiate Baseball League and under Mitchell's guidance, they won their first regular season championship in 1936 with an 8-4 record that tied for first place with Dartmouth.