In 1945, Mathews entered the United States Army and coached football, basketball, and baseball for Fort MacArthur. Upon his discharge a year later, he was a player-coach for the Chicago Rockets in the All-America Football Conference before joining the San Francisco 49ers.[2][4] He returned to UCLA as a backfield coach in 1948 and served in the same position at Arizona the following year.[5][2] He coached at Arizona for two years; after the 1951 season, amid turmoil involving incumbent head coach Bob Winslow, Mathews was suggested as his successor by the team's players, but the program instead hired Warren B. Woodson who did not retain Mathews. Mathews remained in Tucson as a businessman.[6][7]