The QB controversy is going to continue all season long. Say Trevor wins the starting job in the pre-season. Does that mean he keeps it all season long, if Paxton shows signs of improvement? NO.It takes time and to add to it you have a QB controversy which means whoever starts will not have maximum reps in the new system.
If he struggles or the team loses they will not hesitate to throw in Lynch. And the same thing goes for Trevor if Lynch starts. Either QB will be on a short hook, because this is still viewed as a championship defense and you don't want to waste that with a QB who is not doing his job well.