It's interesting to ponder how well Alex Smith would have done if he had the chance to sit for 3 years behind a quality starting QB. It's the same with David Carr, Tim Couch etc.
Rodgers, in many ways, inherited the ideal situation. He got the chance to learn behind one of the greatest players of all time. Moreover, he's inherited a pretty good team, something which most first overall picks do not (assuming if San Fran would have passed on Smith they would have selected A-Rod.)