I have no problem with a new coach interviewing the existing assistants and, if he wants to keep some or all of them, doing so. I have a major problem with an AD telling a new coach he has to retain certain assistants. To me, the second sign of trouble in the Bzdelick hire (the first sign being Bzdelick's pathetic overall record as a coach) was the fact that Ron forced him to keep the assistants apparently without even interviewing them, and Bz was so pathetic that he accepted this as a condition of employment.
As to Chill and Battle and Rusty individually, like most posters I am not in practice and even if I was, I wouldn't know whether they were doing a good job or not. But we have heard from knowledgeable insiders that Buzz does not run good practices, he spends a lot of time lecturing, and doesn't divide up the team into position groups for individual work as much as other coaches do. If that is true, Buzz's practice style and obvious handicaps on the recruiting trail may well be seriously handicapping his assistants' ability to do their best work. That's for the new coach to determine, not me or any other fan, and not Ron Wellman either IMO. The new coach will have to live with whoever he hires so it's clearly in his best interest to hire, or retain, the best coaches he can get.