Buzzilla, here is my take. Gailey had more than the required credentials to run a good ship, so I bought into his credentials along with the administration.
I could see his management style of letting the OC and DC coach the players and he would coach the coaches. However, the big kicker in this type of coaching is you have to react fast and make coaching changes when they are not getting the job done.
It it painfully obvious to me, we are getting progressively worse each game. Changes will have to be made now instead of at the end of the year, if the ship is to be righted. I would promote Nix to OC immediately.
I would bring each defensive assistant into my office one at a time. I would ask each assistant their honest view of the defensive coaching problems. I would then bring in Tenuta and ask him his view of the problems. Player personnel would not be discussed, other than, if any coach thought there were some player personnel problems causing dissension.
I could get a pretty good picture of the problems from these discussions mixed with my own observations. I would make the needed corrections immediately, even if it meant placing a defensive assistant over Tenuta. The DC would still get his years pay, but would lose the DC spot if required.
It is possible, there is another defensive assistant that is totally inept in his duties, or maybe more than one.
There is no reason to wait until the end of the year to make changes when they need to be made now. If Gailey can not see this and lets the ship sink this season, then give him a "thank you for trying" and send him on his way.