I don't think it helps much though. For QB, a lot of difficulty is in developing chemistry with your receiving core, getting used to the speed of the game, etc.
Grey shirting through fall may have given him a glimpse at the speed, and camp this year will give him another, but I don't know if those limited experiences will be enough for the game to "slow down" so he can settle in and put his skills to use.
Grey shirting two years ago doesn't really do anything in helping him develop chemistry with the receiving core, as we have a whole different set of receivers now. Red shirting the year immediately prior or waiting until your sophomore year means you've had a full year to work on timing with receivers who return from the year before.
Maybe if he's a "quick study" like Anae says and can get the game to slow down, he can develop enough chemistry with our receivers after 6-7 games to run a simple offense. However, I think that was just coach speak.