Getting drafted has nothing to do with whether or not he has performed at a high level for two or more years or even any years. You guys mocked me when I told you that DJ Humphries would go high despite his poor play. It's all about the measureables and what you they think they can make you, not what you did in college. Grier has a good (but not great) arm, a lightning quick release and excellent accuracy. He will be rated highly, probably as highly as anyone.
I'm not impressed with the family's mindset. I won't be surprised at all for him to leave.
Usually it is a little bit different with QB's though, since it is much about experience, learned skills, cerebral aspects, etc, as it is athletic talent. Rarely does a true freshman tear it up as QB, but true freshmen quite often do with other positions. The NFL isn't going to waste a 1st round, and probably not a 2nd round on such an unproven. Maybe 3rd round. For every additional year he plays if he continues to progress to his apparently potential I bet he pushes himself between a half to full round each year. With his skills I could easily see him being a 1st round pick in a couple of years...but not now or anytime soon.
As to the family's mindset, maybe. I haven't been a fan of some of the things I have seen, but I kind of wonder if we are just overreacting given the particular situation. I would think the father, given his QB college experience and as a coach would know his kid would benefit from a couple of years experience and maturity before jumping into the cluster**** that is the NFL.