Campbell is better than Toure? You must have rated him fairly highly until he wanted out?
We all have a bit of revisionism when it comes to ex players who leave in circumstances we're not happy with but if he was that far down your pecking order how come he played every week (granted Vermaelen wasn't there at the same time, and possibly Sol for a lot of it so may have answered my own question!).
I said before Toure was sold that he was a liability. So did most fans, we knew something was bad at the cb pairing and most actually went for Gallas staying rather then Toure. This was despite Toure being a popular figure while Gallas hardly endeared himself at times so you can imagine how bad things had got. Kolo Toure couldn't jump and he had the positioning sense of Micah Richards, this was ok when he was younger, quicker and had Sol and Jens along/behind him. Once his pace left Toure, he got very badly exposed for his lack of defensive know-how, he kept trying his best but he just wasn't clever enough. We liked him, we still do I think if we think of him but he just wasn't good enough
The whole Ade thing is possibly a bit of bitter revisionism

If Ade could have kept his ego in check, probably would have been our main striker
As for Wenger, he can be stubborn with his favs, it was probably a mixture of trying to play Toure back into form (he even moved him at rightback to keep him playing) and I think his starting to dislike Senderos as player after that CL/Liverpool defeat left Senderos in tears. Knowing Djourou, he was probably injured at the time as well.
Speaking of which - whatever happened to Michael Johnson? I know he was injured for a while and came back pretty fat but wasn't there talk of his attitude not being right?
I recall that as well