Bill Mills was a native of Boston, Massachusetts. After a strong high school career in sports, he attended the College of the Holy Cross in Worcester, MA, where he played both football and baseball from 1939 to 1943. "Buster" as he was sometimes called, enjoyed a spectacular senior season as the Captain of the Crusaders baseball squad, hitting an incredible .586 to lead his team and the league. The scouts came calling and Mills signed with Connie Mack and the Philadelphia Athletics in the fall of 1943.
Buster, who had been rejected by the military draft because of a perforated ear drum, started his professional baseball career with the Lancaster Red Roses of the class B Interstate League in 1944. With the war in progress and baseball short of manpower, he was soon called up to the Athletics and made his big league debut on May 19th. He appeared in 5 games, including one behind the plate. He was used primarily as a pinch-hitter and had a total of four at-bats. Buster managed one base hit, giving him a life-time average of .250. This would be the sum-total of his major league career. Bill finished out the 1944 season with the Toronto Maple Leafs of the International League, playing little and hitting at a .176 clip.
Buster was out of baseball in 1945 but returned in 1946, hooking up with the Providence Chiefs of the class B New England League for the next four seasons (1946-1949). The catcher-outfielder hit .303 in 1946 but probably his best year came in 1948 when he hit .294 with 10 home runs. Bill had five seasons in the minor leagues, finishing up with Providence in 1949 at the age of 29 with a career .286 batting average.