The decision to keep Butler as LeBeau's successor was make a long time ago when LeBeau's defense was good. Remember, when Butler took over we wondered if a guy who spent years in the old system would be able to change things enough to have an effective defense again. IF the Rooneys believe in Butler and IF they keep him then they need to tell Shades to sit down and STFU and let Butler coach the defense the way he wants and draft who he wants. Then it will either work or it won't but right now it mostly isn't working. That being said, if I ran the team after the season I'd fire every defensive coach (except for Tom Bradley because he's only been here this year and not responsible for the clusterfuck).
Granted at the time the rules were better for defense, but Cowher was literally 99-1 in games where he entered the 4th quarter with a double digit lead. Shades blows more 4th quarter leads than that in one season.