I saw Grier play in high school, standing on the sidelines to observe a couple of times. Yes, he played in a lower classification against lesser athletes but I believe he can be the next "guy" at QB. He has a strong arm but more importantly, is very accurate. Most every pass he threw in the state championship game was delivered on target, allowing the receivers to catch it in stride. He moved well in the pocket and showed an awareness of the pass rush around him. Don't think he has elite speed but he's quick and ran effectively when necessary. In short, he looked like a functional quarterback should.
My guess on the desire for a redshirt season would be related to bulking up some size-wise and getting used to the speed of the game on an elite SEC level. I am anxious to see what he can do in McElwain's system with effective coaching. I think the skill set is there.