Getting rid of a long time coach is always a dicey proposition, especially one that has been successful. Only in hindsight can you be sure what should have been done. There is historical evidence to support both sides of the debate. Even though I have little confidence that Bob can turn this around I think the next step is to do some substantial house cleaning with the assistants. By substantial I mean we should have more new blood than retained coaches.
I think Bob needs to decide exactly what he wants the team identity to look like then hire the coordinators he feels can do that, then let them run their systems. I believe going forward Bob needs to give his OC and DC more autonomy as well as demanding accountability based on some set of objective criteria. Of course all of this is predicated on making the correct hires.