This is a very tough question to answer. Because to a large extent the problem is not Gailey, but injuries and questionable personnel moves by Nix. It was a mistake to think Merriman could handle the return back without a really good plan B option if he didn't work out. This defense is void of good LB's (Except Nick Barnnet) and the corners are average at best. We have no pass rushers to speak of. This defense needs two good drafts and at least four FA's to shore up this defense.
What I do lay at Gaileys feet is the lack of adjustments offense wise. I dont see any new wrinkles at all. The offense is predictable and defenses now know how to shut it down. This is partly due to injuries.
So unless you fire Nix and Gailey and have great replacements lined up, we might as well let these guys try to work it out and wait for a new owner to clean house. In the mean time, cancel press conferences and put up a sign saying we are working on it.