Mancini was an abrasive character but that's probably what we needed after the largely ineffectual Hughes. He did indeed make us winners but being abrasive will only take you so far. It's a short term strategy. I suspect Peter Reid was much the same.
The problem really came to the boil with Marwood, who was effectively DoF (but without the title). Mancini had no intention of working with anyone other than his own coaches and the club tried to sidestep the issue by moving Marwood to the 'Football Administrator' role.
However things really came to a head when we appointed Soriano & Begiristain. Khaldoon was insistent that we would have a proper management structure which involved a Director of Football whereas Mancini wanted to do it all himself. That was in the 2011/12 season, prior to the PL win. The club tried hard to convince him but ultimately he was apparently rude and disrespectful to the owner and chairman.
If he felt he could do that to them, then sure as hell he felt he could do it to lesser mortals. The club knew his time was up when even total professionals like Zabba and David Silva were complaining.
Chappy's major role (even more than managing the kit) was to foster a good atmosphere in the dressing room, as he was the member of staff players had most interaction with. Mancini. on the other hand, eventually poisoned it.
I can certainly respect Mancini for what he did for us, delivering two trophies. Perhaps he even needed to be a bit of a bastard to do that. But that will only take you so far and I don't understand people knocking a genuine person like Chappy, who in his own way played a major role behind the scenes, just because he happened to speak out about a complete lack of civility. You have to work with people and you work better with them if there's mutual respect.
Perhaps I'm on Chappy's side because (a) I've heard more than most about Mancini's behaviour and (b) it reflects an incident in my current role, where we originally had a key team member who was regularly rude to everyone. He got shipped out and while I could agree with some of his work-decisions, I had no respect for him and the team was a much happier and more productive one when he was replaced.