You say a lot of players made mistakes in the game, let's go with that.
If you saw a def back who had gotten old and slow, and WR's were running by him easily, you would say he needs to be replaced even if he has been a better corner with more experience than his replacement.
He lacks an important skill required as a def back.
He will never get any faster, or as fast as he used to be.
He can never show how good a cover guy he is because he isn't fast enough to stay with the recievers.
Now look at that scenario as a QB.
Bledsoe has gotten old and slow. He is still a good passer and a good QB, but like the def back, he lacks an important skill needed to play the position.
If you put the def back in, yes you will have growing pains as he learns the ropes, but WR's won't be running past him because they are faster than him.
The same with Romo, he will have growing pains, but all in all he brings some mobility to the position so defences can't blitz all of the time without feeling consequences.
I realize Parcells is not going to change soon, you are right, he has said as much, but I am just explaining why I don't see it getting any better as time goes on.
We are between a rock and a hard place here.
Bledsoe is too slow and immoble to show that he is still a good passer.
This better says what I have tried to say, ...
http://cowboyszone.com/forums/showthread.php?t=66751