People have the misconception that you have to be very intelligent to be a NFL Quarterback. Not True. You have to be very intelligent in terms of NFL FOOTBALL schemes and strategies, not in terms of natural intelligence that, say, Mensa would measure. Dan Marino scored the same as VY (2nd time) on the wonderlick (which is a stupid, stupid test that doesn't have anything to do with football). Dan Marino isn't a brilliant guy. Many of us are light years ahead of Marino in terms of intelligence, but Marino is light years ahead of us all in terms of pure football talent at the QB position. Best QB stat wise who ever lived. Now, I don't think VY will be in the same regards as Marino, but don't underestimate his ability, football intelligence, and sheer willingness to do whatever possible to win. Joey H. is an intelligent guy who isn't a winner. Joey H. doesn't have the tools or intangibles that VY does. I see VY doing very well in the NFL.
As for Leinart, his problem is that his shoulder is suspect and he throws some of the ugliest balls I've seen in a while from a top flight QB. The guy isn't half the talent that Carson is and doesn't have the arm cannon that he'll need in the NFL. His wounded ducks got things done against the Fresno States, Notre Dames, and Oregons of the world, but any decent NFL corner or safety will gobble those up in a hurry. His margin for error is extremely slim and his timing and release are going to have to improve exponentially to even begin to make up for his throwing troubles.