Where Tony Romo stacks up all time

Tony Romo leaves as the Cowboys' franchise leader in passing yards and touchdown passes. Tom Pennington/Getty Images

Tony Romo has decided to retire from football, according to league sources. Though the last two seasons of his career were shortened by injuries, Romo is among the best quarterbacks in Dallas Cowboys history, and one of the best undrafted quarterbacks ever.

An impressive career

Romo joined the Cowboys in 2003 and threw his first pass for the team during the 2006 season. Since then, he has become the franchise's career leader in passing yards (34,183) and touchdown passes (248).

His 248 passing touchdowns are the ninth-most in NFL history among quarterbacks who played their entire career with one team.

Romo ranks third in quarterback wins in Cowboys history with 78, trailing Troy Aikman (94) and Roger Staubach (85).

Romo has a career passer rating of 97.1, which is the fourth-best in NFL history (minimum 1,000 pass attempts), trailing only Aaron Rodgers (104.1), Russell Wilson (99.6) and Tom Brady (97.2).

Romo was signed an undrafted free agent. He ranks fourth in passing yards, third in touchdown passes and fourth in starts among undrafted players since 1970, according to Elias Sports Bureau research.

Though Romo had an impressive regular-season career, his 248 passing touchdowns and 34,183 passing yards rank second and fourth, respectively, among players never to play in a conference championship game, according to Elias.

What might have been

In Romo's first nine seasons since becoming Cowboys starting quarterback during the 2006 season, he started 123 of a possible 138 games. Over the past two seasons, Romo only started four of a possible 32 games.

In the 2014 season, the last one in which he played the majority of his team's games, Romo was among the league's most efficient passers. He led the NFL in Total QBR at 81.6, his career best (not including his six snaps in 2016), and completion percentage (69.9 percent), best in a season in Cowboys history. He also led the NFL in passer rating (113.2) and yards per attempt (8.52) and was second in touchdown-to-interception ratio (3.8) among qualified quarterbacks that season.

Cool in the clutch

From 2006-14, Romo led 27 game-winning drives in the fourth quarter and overtime. That is the most in the NFL over that span, one more than Peyton Manning and Matt Ryan.

From 2006-15, Romo completed 65 percent of his passes and averaged 8.4 yards per attempt in the fourth quarter, which is the best of any of the 36 passers with 500 action plays in the fourth quarter in that span. His yards-per-attempt average in the final quarter of games was over a third of a yard better than anyone else in the NFL during that span (Cam Newton, 8.03).

Seventy-five of Romo's 248 career touchdown passes came in the fourth quarter. That's three more fourth-quarter touchdown passes than Staubach and Aikman had combined.