4. Jon Kitna (2009-2011, 2013)
When Tony Romo was starting out his career as the Cowboys quarterback, the coaching staff felt the need to have a veteran backup. Early on, it was Brad Johnson who signed a three-year deal in 2007. A former Super Bowl winner, Johnson gave Romo an excellent mentor but when he was called into action, he struggled to get the job done.
This led to Johnson being released and the Cowboys replaced him with Jon Kitna who was previously a starter with the Detroit Lions, Cincinnati Bengals, and Seattle Seahawks.
It wasn't long before they had to turn to Kitna as Romo suffered a broken clavicle against the New York Giants (which happened when Chris Gronkowski forgot fullbacks were supposed to block players that decided to blitz). At this point, the Cowboys were just 1-5 and it seemed the season was a lost cause.
Even knowing they were never going to make a run to the playoffs, Kitna helped them improve overall. He was under center for nine games and Dallas was 4-5 in those contests — and 1-0 with Stephen McGee who had to make one start in place of Kitna.
The 38-year-old Kitna completed 65.7 percent of his attempts for 2,365 yards with 16 touchdowns and 12 picks. While the interception numbers were high, he proved to be a solid addition and was never afraid to make the big throws.
He returned in 2011 and only played in spot duty. Kitna was trusted enough by Jason Garrett that he was coaxed out of retirement in 2013 and backed up Kyle Orton who had to start in the season finale.