I think Coach Ferentz can come under criticism for not getting rid of Coach K before extensive damage was done. I say that while generally being a supporter of Ferentz. Ferentz is not only conservative by nature, but he also has a tenancy to hunker down, to stick with the status quo despite indications it is not working, and avoid making critical decisions. In this case Coach K's behavior was clearly toxic, but Ferentz continued to give him the benefit of the doubt far too long.
Thankfully Reese Morgan's skills at developing talent are second to none and he has the defensive line pretty much back where they should be.