Also Matt Leinart is a very good rookie qb on par talent wise with Peyton Manning or Eli for that matter as well.

Yerre crazy man. CRAZY.
I am no longer predicting a complete flop for ML in the pros since he landed in maybe the best possible situation out there, but to compare Mr. Noodle arm with Peyton is a huge stretch.
Remeber that this kid had a HUGE talent advantage teammate wise vs almost every team he faced in college. With the higher speed of the NFL game along with the much more even playing field, he's going to have a very tough time living up to these standards.
Do I think ML will be a total bust? Not neccessarily, especially since he will have Fitz, Boldin and Edge. Will he struggle as a rookie? Probably. Will he ever be able to compare with Peyton Manning as the best QB in the league? Don't think so.
Matt will have every opportunity to succeed and should do so given his surroundings, but to compare him with P-Man is way, WAY premature.