a football and track star at carlsbad high school in carlsbad, new mexico and at the university of denver, mahaffey put university of denver football on the map in 1954. mahaffey's still name dots denver's record book. an honorable mention all-skyline conference member in 1953, mahaffey broke out in 1954, rushing for 813 yards and 12 touchdowns while earning all-america and first-team all-skyline conference honors. finishing ninth in the country in rushing yards, he and teammate fred tesone formed one of the top rushing tandems in the nation as the two combined for 2,528 yards, outrushing their opponents by over a 2-to-1 margin and helping the pioneers to a 9–1 record, the first outright conference championship since 1917 and the second-best season in school history. he is the school's all-time leader in rushing yards (1,605), touchdowns (27) and points (163) and ranks second in all-purpose yards (2,942) and third in total yards from scrimmage (1,788).