Mahoney entered Holy Cross in 1908
after starring for four years at Lewiston High in Maine. Although
he never weighed more than 136 pounds, he made the varsity
football, track and baseball teams in his freshman year. He was the
regular quarterback of the 1908, 1909 and 1910 Crusader football
teams and directed the attack in the Fitton Field dedication game
In track he equaled the 40-yard dash record of the period and was a member of a track relay team. After playing third base with the varsity baseball team in 1909, he captained the 1910 team and signed with the Cincinnati Reds after the first two games of the 1911 season and left Holy Cross.