Let be honest, the Italian league isn't exactly bristling with top class competition. Any club that spent well and benefitted from some shrewd business could have dominated the Italian league.
When you have:
Vidal, tevez, pogba, Buffon, Marchisio, chiellini, LLorente you are going to do well in the Italian league.
I don't doubt that he is a good manager but winning the Italian league at the moment isn't hard with a good team and his successor has done even better. Is Laurent Blanc a top manager? Taking PSG to easy league titles and getting to late stages of the CL?
He may be amazing but I don't think he would be that high on the list of managers most Chelsea fans would like. I may be wrong.