As reserved as Staubach appeared, his competitive drive was unmatched. He threw a paddle at a larger teammate once when he lost in a game of ping-pong.
In Super Bowl 13, which the Cowboys lost, he threw a 3rd down pass into the endzone and future Hall of Famer, Jackie Smith, flat out dropped it. Staubach looked as though he expected to be given another chance. He had difficulty processing the fact that they didn't score. He was that focused on winning.
Back then the Cowboys were expected to win. Any time they were defeated it was considered an upset.
Staubach had the best passer rating in his first season as starter. He had the best passer rating in his last season. He led in passer rating four times.