That's the NFL: Not For Long. First year's a welcome year. Second it's, What are you going to do? Third year's like, Well, you didn't do much last year; give us something or you're going. That's the way it is. They'll trade you or they'll cut you.
As a quarterback your job is to drop back and give it to the open receiver, let them run. Obviously, there are times when you get some pressure and you have to make decisions, step up in the pocket and buy time for your receivers and deliver the ball.
I think you get in a situation where once you start hearing the boos and hearing the radio stations talk and people on the outside begin to bring your name up of being benched, then you begin to lose focus, and now your play begins to fall and you begin to focus on other things.