With Barzagli, I see a guy with a pissload of potential, but at this time, to bring him in as the defense lynchpin is foolish. Right now, Barzagli needs to be apprenticed by an experienced, world class defender to help him boost his confidence and hit the next level. Grygera is the closest they'll have at their disposal, as Birindelli, Zebina and Boumsong are, frankly, not good enough to really take someone like Barzagli (and Criscito for that matter) under their wing.
Either that, or someone at the talent level of Milito, Luisao, Alex, etc. to be that leader while Barzagli matures.
He's definitely not the answer alone, but has the makings of the next great Italian defender if properly groomed.