I don't know if he is rattled or not, but he is playing like it. It's hard losing your starting job and then have to go back and gain the confidence of the team. It looks like he is afraid to make a mistake. When you play scared like that, your natural abilities can't take over. For example, for all you golfers out there. It's like constantly slicing the ball and then all of a sudden, you have houses on your right and left. You short arm everything because you are afraid of the outcome. No different here. He needs to calm down and play an not worry about Pelini getting in his face.
Just my thoughts.