Well, it's of course easy to point at projections a few years afterwards but...
I think the "Aaron Rodgers-example" clearly highlights how a team can be rewarded if they are patient enough to let their quarterback develop behind a proven starter instead of throwing him right in there from the start. Granted, Rodgers has special tools but a quarterback always needs to refine his skills and develop before fully adopting to the pro level.
If you're looking for long-term success in the NFL you need solid play from the QB spot we all know that.
In order to make the transition from new to old QB rather seamless the teams needs to give the young guys the chance to develop their skills behind a veteran.
If adopting that theory it is my belief that NFL teams would have a higher success-rate at developing quarterbacks. Not everyone will be as good as Aaron Rodgers, cause he might be a special one, but in my opinion they would be better on average than the young guys are now.
You could of course make a case for rookie starters like Flacco, Ryan, Sanchez and Freeman (the latter didn't start immediately) being succesful lately. I still feel there's not enough evidence to fully judge their success. I think a case could also being made for them hitting their ceiling earlier since they haven't been able to learn the craft from a seasoned veteran. There are also several examples like Ryan Leaf, Akili Smith, David Klingler, Heath Shuler, Tim Couch, David Carr, Joey Harrington and several others that were thrown to the wolves too early. Taking the easy route would be saying that they were not good selections (and they weren't of course) but that does not diminish the fact that maybe they needed a little more time to develop. Most of those guys would not have been in Aaron Rodgers class if afforded a little time but I'm guessing at least someone on that list could have been at least serviceable if teams would have been more patient and had a plan for dealing with QB-succession.