Yea there is a way, Rattler earns the starting position in training camp, and you tell Carr he is the back up and if you don't like it leave or shut up accept it. You make Rattler TAKE Carr's job from him fair and square, if Carr can't handle it then that is his problem.
I don't think Rattler is better QB then Carr right now. Carr is not the QB of the future but if you care about winning now he is, at least in my opinion, the better QB.
I would rather move on from Carr and let Rattler start because I know Carr is not the long term answer and I would rather suck and find out what we have with Rattler, then have another 2 years of mediocrity with Carr.