The point is that he has to play one more year under his current deal just as well as he played last year...in other words, if he is to be paid like one of the 2-3 best linemen in the league, he must play like one of the best linemen in the league.
From his perspective, an awful lot is hinging on his level of play this year. If it were you, would you want every chance you can get to know the new playbook like the back of your hand, be in the best shape you'v ever been in your life, have the maximum amount of chemistry with your teammates you could possibly have, and take reps in the preseason to shake off the offseason rust...or would you want to avoid as much as speaking to your offensive coordinator until a day before the opener, having not lined up and taken a snap for about 10 months?
Can Peters overcome these things? Yeah, he's a great athlete, and he's capable of it. But he's made things harder for himself than they needed to be, and he's gained little to nothing from it. Lets see if he comes out and earns the big bucks he's been after.