My position was (and is) based on seeing how high-profile "can't miss" and "sure starter" newbies (either recruits or transfers) haven't turned out as expected (Zwick, D'Andrea, Kerr, etc.). Hell, nearly everyone had Schlegel beating out D'Andrea for the starting spot in 2004 (but he didn't), although Schlegs turned out pretty good in the long run.
Keep in mind the level of competition that Grant has played at...he hasn't seen near the speed, complexity, and intensity of I-A football. Many also dismiss the importance of Laurinaitis playing in two very-high-profile games, regardless if he only played 25-30% of the defensive plays. In my mind, it's far more reasonable to pencil in a kid who was his state's HS player of the year, who has a full year in system, who has played special teams all year, and who has started in games against both Michigan and Notre Dame (along with mop-up duty in other games) over a kid who has never set foot on a I-A football field. Hey, if Grant actually is better than Laurinaitis, then we got the "steal of the class" in linebacking recruits this year.