Steve Young
Young’s career began in strange circumstances as he played for the L.A. Express of the USFL. After he left them he joined the NFL’s Tampa Bay but failed to impress. He had a single season as a regular starter but nobody predicted that he was a future Hall of Famer. Eventually, he wound up in San Francisco as Joe Montana’s backup (via UPI).

One quarterback’s injury is another’s opportunity and this proved to be the case for Young. Montana had a brutal elbow injury and didn’t play in 1991. Suddenly, Young exploded into life and proved his incredible talent. In the end, San Francisco allowed Montana to leave because Young was too good to sit on the bench.