-if he was a definite improvement over Bledsoe he would have been the starter at the beginning of the season.
Then you haven't followed Parcels long enough; he favors veterans, sometimes too long.
-you dont need to be considered a great QB to lead your team to the Super Bowl ask Dilfer, Brad Johnson, Jeff Hostetler, Doug Williams and that is only in a span of 10 or so years. many average or below average QB's have won Super Bowls.
Obviously; here in NY we saw that first-hand with Hostetler. However, the weaker the overall team the more the onus is on the QB. Since you brought up Hostetler you should know that Parcels didn't want to play him, in the same way he didn't want to play Romo-Hostetler only got in because of injury, not because of Parcels' wisdom. The rest, including the fact that Hotetler was more mobile, was good fortune-If Simms hadn't gotten injured it's unlikely they'd have gotten past SF that year IMO; they'd been unable to beat them with Simms standing there.
-he may be immobile but there is nothing wrong with his velocity, that is insane. he will have NFL velocity at the age of fifty. he can throw the ball through a brick wall. im not saying you need a rocket to be successful.
I said velocity and accuracy. Second, he does not consistently throw the ball on a line anymore the way Romo did last night. Third, mobility. Romo's got the mechanics, only needs the experience to understand what to avoid. If Bledsoe wasn't such a jerk he'd be speaking with Romo, helping him understand the game.