You can't give up on Alex just yet. Look at what he had to work with. This year he has better recievers (hopefully Arnaz stays healthy), and I'm not sold on the OL just yet. There should be quite a bit of improvement with Norv Turner there as well. A lot of people want to label him a bust, but you need to wait until at least the 3rd year, just ask Drew Brees.
Rothliesberger is the exception, not the rule. Even then, he wasn't required to take on as expanded a role as most QBs.