Leahy was an All-American quarterback for the Hornets in 1968. He earned first-team All-CIC and NAIA All-District 10 honors when he threw for 1,698 yards and 17 touchdowns. He went on to play in the National Football League for two years with the Pittsburgh Steelers (1970-71), playing behind Terry Bradshaw. Leahy began his coaching career in 1973 at University of Pittsburgh and has coached at seven NCAA Division I schools. Professionally he was the quarterbacks coach for the 1983 USFL Champion Michigan Panthers and also coached with the Minnesota Vikings and Buffalo Bills in the NFL.