This arguement is going to go around in circles. Someone will say an example of a QB who fails (ryan leaf), another will say of someone who was good (peyton manning), and then we will get the examples of those who start strong and then fade, and those who start slow and then come into their own (eli manning).

the point is that some quarterbacks, reguardless of their system, just adjust better to the league than others. this is why it is the hardest job and why everyone wants to be the QB when they are playing in the back yard.