he should strongly consider hiring a DC with experience (success) in the role of defensive coordinator. His last three promotion from within coordinators (counting Doman as OC) have failed miserably. If he wants to use disciples of his defense, then fine, but the evidence is showing he is not preparing them well enough for coordinator duties. If you aren't able to prepare them from within, then you need to do what the majority of P5 programs do, and that is hire a coordinator that has had experience in the job, and therefore, is not such a risk/unknown.

What does this mean? It means either a) let someone else run their defense, or b) let some of his disciples go elsewhere to try their hand at coordinating, and bring them back once proven successful.