There is little doubt that whoever is hired is going to be high profile. Stan has no choice in this matter (and yes, I understand that high profile is relative).
But a Harbaugh, Saban, Meyer, even Gruden is going to demand to institute his own people. Perhaps even McDaniel.
Might there be holdover or two (such as Fassel)? Yes.
But on the O staff, I imagine zero.
On the D staff, probably zero, but maybe Wauffle. I can't see GW being kept. He needs to do things his way, which is usually a bit unorthodox.
And, if it was me being hired as HC, I'd want to clean house.
A fresh start is needed; no left over loyalty to the previous regime and no leftover locker room loyalties.
Wouldn't surprise me to even see the training and strength staff let go. Again, loyalty issues.
