The issue is fans think guys are amazing until proven otherwise. That mindset means they'll always prefer the untested to the proven, because few players prove to be what fans hope.
Coaches, meanwhile, have almost the opposite view. A kid is unproven until he proves something. We see the failings of some guys on the team. Coaches also see what they've done (game time and practice), what they know, how serious and hard they prepare, and the lack of all that by others.
I'm not defending all their personnel decisions, but the monotonous repetition of this discussion for most of 2 decades tells you it's not about one staff or their behavior. What it's about is we haven't recruited enough underclassmen who can legitimately take food from the plate of juniors and seniors. The NFL draft ends up confirming this, as our talent pipeline has dried up a ton. Fans think every promising recruit is the next ____. Well, they haven't been, not for a long time around UM.'