I don't care how big of a QB you are, that many hits are career shortening. Few of those hits are of the running back "shoulders square, impact absorbing" variety. Many QBs have a good one or two seasons, and then they drop off due to injuries or defenses figuring out their tendencies and strengths and forcing them away from them. Those QBs who can adapt, or who have abilities beyond what can be reasonably contained are the ones who put together long, successful careers. Brees' accuracy, Manning's playing calling and quick throws, Roth's ability to extend a play and find that open receiver put them ahead of most. The latest addition, I believe, is Andrew Luck in that he goes through his progressions faster than anyone I've seen. Perhaps he's just looking off safeties a good bit of the time, but to me it looks more like he has that grasp of the patterns to know his first four options and is adept enough to consider them all. For a receiver, knowing that you're the third or fourth option, but you better be ready for the ball, keeps them digging and makes it all work.
RTR,
Tim