Not unprecedented, but uncommon. I made it through the about 100 D1 basketball programs before I stopped and ~5% jumped from D2 or lower to D1 HC. The most common route for these coaches seem to be HC at a lower school, assistant coach at a P5 school, the D1 HC.
He’s in his mid-40s now. If he wants to move, I would expect him to do it soon. The more common path would be him moving to Rick Barnes staff for 2 yearsa, then to a D1 HC job.
My hope is that what ever M&M think, they pull a George Constanza and do the opposite. Their instincts suck. If they don’t think someone like Schertz can do it, then he should get the job. If they think he’s the man for the job, then we should run away like he has the plague. The key is finding out what M&M want and then do the opposite.