Peterman is a solid number 3 NFL quarterback. He is probably the perfect scout quarterback. Little salary. Very smart.
While he does not have an NFL QB arm, he has an NFL QB mind. Much of his failure in Buffalo had to do with a poor offensive line and poor receivers. People forget that Derek Anderson, who played 13 years in the NFL, looked just as bad as Peterman. Anderson threw 4 interceptions and 0 touchdowns while in Buffalo and didn't survive the season due to that line. Tom Brady would have struggled with the offensive line and receivers the Bills put on the field. It was arguably the worst offensive line/receivers combination any quarterback has ever played with. McCoy even struggled running the ball due to the line and receivers.
Anyone who thinks they know more about quarterback evaluations than Jon Gruden is living in make believe world. The guy knows QB talent better than anyone in the game. If he thinks Peterman is an NFL quarterback then Peterman is an NFL quarterback. I would not be surprised if Peterman lasts in the NFL as a backup for another 10 years.