I'll try to focus on just one area for you. You are correct in that the Big 12 is a better defensive conference than the Pac 10, but the other side of that coin should tell you that Vince Young's numbers would have been better in the Pac 10 too and Leinart's numbers would have been worse in the Big 12. Also, if the Big 12 defenses are better than the Pac 10's, then that means that the Big 12 defenses are closer to NFL quality, thus inferring that Vince Young would be a better pro than Leinart and Cutler as well, since he didn't elevate his teams' play the way Young did.
You keep bringing up Quincy in this discussion for some reason, usually to make some negative statement about him when he has nothing to do with Young or Leinart, but for all Quincy's faults, he put up respectable numbers overall in 2003 in terms of td's and yardage and was the main weapon of offense. He had to face defenses like Buffalo,New England,Miami,Philly,Tampa,Carolina, and went 3-4 with no possession receiver over the middle and no legitamate RB, contrasted with those teams backs like Ricky Williams,Warrick Dunn,Steven Davis/DeShaun Foster,Travis Henry,Antwan Smith/Kevin Faulk,Brian Westbrook. Every single team we played against had a better running back. That was Parcells fault and he acknowledged the error by trying to trade 3 times that year for a decent running back. If Quincy had had a halfway decent RB that year, he would have thrown for another 300-400 yards and over 20 tds. I know that is true because our receivers dropped some 29 passes worth probably 300-400 yards.
So if you take away the drops and add a decent running back,Quincy would have been a 4,000 yard qb with 25-30 tds and those my friend, are pro bowl numbers. So say all you the negative things you want about Q,considering the schedule and supporting cast, he did a pretty fair job and you would see that if you took the blinders off.