Damocles said:
Madness; utter, utter madness.
Carlo is one of the greatest coaches in the world, and the shit he has put up from dickhead owners at both Milano and Chelsea means that he has the professionalism and patience of a saint.
He's been a manager for about 15 years and has won 2 Champions Leagues, 2 Leagues, the World Club Cup, won Manager of the Year twice including the Best Coach in the World.
You judge managers on what they have won, and the reality is that he won the double last year, then finished 2nd this year. Saying truisms like "there have been a few mistakes" is daft; every coach on the planet makes mistakes, even Guardiola, Ferguson and Mourinho.
The fact that you think Chelsea are "above the level" of Carlo shows you everything that you need to know about Chelsea. Carlo managed Milano for 8 years, to great success.
I wouldn't call Carlo a world class manager by any stretch. AC Milan were left in a difficult situation when he came to Chelsea, a situation they're still recovering from. Clear evidence of that being what Spurs did to them in the CL. For a European powerhouse to be dismantled by Spurs in such a fashion exasperates the lack of long term foundation his legacy left there.
I realise that it isn't fair to pin Milan's failures on Carlo when he wasn't in charge at the time, and I'm certainly not doing that. However, that was largely his squad just as this Chelsea is largely Mourinho's squad. One of his biggest problems is handling transition. He never gave new talents a chance in both Milan and Chelsea when both clubs were crying out for it. He's afraid to change the status quo.
Carlo’s departure was always going to be a sad affair, not least because of his affability and genuine niceness, which in itself did not make Roman’s decision to dispense with his services wrong, it only made it seem that way. However if you had watched Chelsea every week since his arrival, you would understand fully why he was let go. His team selections and tactics were often found wanting. He lost 4/4 rounds in our important CL knockout ties.
You say you judge managers by what they've won (in the past). Its much more reasonable to me to judge them on what they're doing; and his attempts to build on his progress were futile in almost every aspect.