Born in Mahanoy City, Pennsylvania, and later attending Hillhouse High School in New Haven, Connecticut, Dugan went directly from the College of the Holy Cross to the major leagues.

[4][5] He made his major league debut at the age of 20 with Connie Mack's Philadelphia Athletics on July 5, 1917.

[6] He was moved permanently to third base in 1921, and would be a steady .280-.300 hitter as well as a fine defensive third baseman for the rest of his career.

[10] Dugan had his most productive season in 1923, when he hit .283, scored 111 runs and led the league's third basemen in fielding percentage to help the Yankees win their first world championship.

[1] In a United Press International article, Dugan was proclaimed the hero of the 1923 World Series for his spectacular defensive performance as well as his timely hitting, which produced five runs batted in.

[12] Yankees manager Miller Huggins named Dugan as his leadoff hitter at the beginning of the 1925 season.