 In the latter capacity, he became known as one of the greatest backup quarterbacks in NFL history.During the 1968 Baltimore Colts season, he filled in for 9 games for an injured Johnny Unitas leading to an NFL championship shutout victory and Super Bowl III, which they lost to the New York Jets.For the 1972 Miami Dolphins season (both under coach Don Shula) he filled in for 11 games for an injured Bob Griese leading to Super Bowl VII and the only perfect season in NFL history.