It's been a pretty lengthy career for Sage Rosenfels. After getting drafted in the fourth round of the 2001 draft he played for five different teams (and two of the twice)--never as the starter. He was always the backup.
And after 12 years in the league he is calling it quits.
Next to finding a winning quarterback there is one thing that worries teams more--finding a good backup for that running back. You know he isn't going to be a superstar; otherwise he would not be a backup. You just hope he is good enough to finish the game, and/or start for a few games in case you need him to.
Sage Rosenfels was that guy at one point for the Washington Redskins, Minnesota Vikings, Houston Texans, Miami Dolphins, and New York Giants.
Over the duration of his career he amassed the yards that a starter would in a single season (4156), had 30 touchdown passes, 29 interceptions (since he hardly practiced with the first team that isn't too shocking), and a career QB rating of 81.2.
Best of luck to you Sage and thanks for trying.