Now now, Im not saying he is the epitome of perfection (that title is reserved for my backside). But he is as good as it could get when you look at it realistically. It is possible that his tactical philosophy just doesnt accomodate set pieces as much as others, but I am quite sure that if he did skimp out on set pieces it was a measured, deliberate decision.
What I did was not to address your question, but to address the root of your question. And as long as there will be freedom of thought, there will be differences of opinion, and there will be people thinking THEIR formation is better, THEIR player selection is better, THEIR ideas are better.
When he refused to give DP a regular first-team spot, at first I was in shock. It was incredibly bold, benching the club's cash cow of the late 90s, the symbol of the team, a player who was at the top of his game, who even Lippi didnt dare bench. But Capello knew exactly what he was doing. He brought the best out of Del Piero. He gave DP a realistic assessment of his ability and his status, and he cc'd a copy to the rest of the world.
When Capello commented that Veron-Pizarro on the pitch together wouldnt work, I thought "What the hell do you know? They arent intended to play together, bla bla bla." Mancio himself disagreed. Sure enough, Mancio played them together. They sucked. He tried it again. They sucked. Mancio put Veron on the flank and Pizarro in the middle. They were mediocre at best. Needless to say, Inter fans were annoyed. Even if Mancini didnt directly address it, it was a slap on the face.
All Im saying is that you can disagree with his methods, scorn his style, disapprove of some of the smaller details- because everybody has their preferences. But nobody has any reason to doubt his capability to haul in the trophies. Yet. Which is what my spidey-sense picked up in your post.