3 - John Skelton
John Skelton saw his success as a backup quarterback transform him into a starter for the 2012 season, though it was short-lived thanks to an injury he suffered in Week 1. But that unfortunate event shouldn’t take away from Skelton’s success as a backup in 2010 and 2011.
He went 7-4 as a starter over his first two years in the league and threw for 13 touchdowns and 16 interceptions. Had Skelton’s injury not sidelined him and led to an eventual quarterback carousel that also involved Ryan Lindley and Kevin Kolb, who knows how it could have altered the team moving forward?
2 - Drew Stanton
The only long-term backup on this list, Drew Stanton spent four seasons with the Arizona Cardinals, finishing 9-4 in that span. He also saw action in 26 games, and while he only completed 51.1% of his passes, Stanton’s ability to manage the game and take advantage of the playoff-caliber talent the Cards had during the mid-2010s fueled his success.