Seems to me that when you are having your worst year in the tail-end of your career since your rookie year? Time to hang up the hat gracefully. I really think he's trying to pull off a Payton Manning deal, retire on a Super-Bowl win. He could have done that a couple years ago, but he stuck to his whole "I will not stop playing until I am 45 YO thing".
Ug!
I doubt if he thought he would have such a bad year. He most likely will hang it up after this year. And yes, he probably wants to pull off a Payton Manning deal like you say. In hindsight, he should of retired a couple years ago like you mentioned. Maybe he is trying to prove that he is still young for the job.