I'm not judging him. I just stated the fact.
Never said that he's a bad defender or that he will fail in serie A. Only said that he's playing bad in the pre-season so far.
Of course, he can be easily excused. New team, new style of football, presure, etc.
I doubt he'll win a spot in the first team anyway, no matter how well he plays. That's if Nesta stays fit, of course. Thiago Silva is so far the only one in Milan who's playing well, and, unfortunately, the guy is quality. He will easily win a starting XI spot.
A fit Nesta will undoubtedly be Thiago Silva's partner in the heart of the defense.
Onyewu will have to hope that one of Nesta/T. Silva will be injured and then he will fight for more minutes with the other defenders on the bench (Kaladze, Bonera, even Favalli).