The great thing about "his" offense is that it's broad enough and flexible enough to "fit" the talent. If you look at the three different QB's GT has had over the six seasons, you'd see that he "tailored" his offense to their talents. If Vad were still here and maintained position as starting QB, he'd still be tweaking the system to fit Vad's skills.
He's not stupid. He's not going to force a square peg into a round hole. We all know he recommended to Renfree that GT wasn't going to be the best place for him. All of the QBs that have come in since have/had the capability of lighting it up in his system, and that includes Vad.