Those grades seem reasonable to me. Nobody on there I would say is considerably off.
Playing a game of "one higher, one lower":
One Higher - I'd take away the minus from AJ Barner's grade. I don't know what more you could have asked from him as a fourth-rounder who was barely involved in the receiving game in college. I know the grade is for the player and not the pick, but the front office and scouting team deserve enormous credit for seeing that potential in him.
One Lower - If whatever it was Christian Haynes was doing didn't earn an "F", then I'm just going to assume they only give those out to players who didn't make the team.