Although Schweinsteiger got the plaudits, Boateng was probably motm for Germany in that World Cup final.He was good for a couple, not world class and he didn't keep up that standard for that long. He played in a comfortable situation where he did little defending. In matter of fact during that 'world class period' he (or the defense) was frequently bailed out by Neuer.
Like I said, when your team only has to defend for 20-25% of a match there isn't as big of a pressure on you as a CB. It's not comparable to being in a team that has 50-60% of possession.
City shipped him off, no one wanted him when Bayern actively tried to sell him. Bit surprising for a supposedly "world class" defender don't you think.
He was also incredible for Bayern during his peak. You won’t find a knowledgeable Bayern fan who will tell you that Boateng’s peak wasn’t outstanding. You’d also be hard pressed to find a Germany fan who’d tell you that either. Boateng’s peak was great. He was head of the defense for one of Bayern’s most successful sides ever.