My best friends are juve fans, so maybe i've been brainwashed by their propaganda, but i'll take a bet that Giovinco wil make it. He's played in Serie A and UEFA cup when he was on loan at Empoli. He has pretty good balance, and as long as he gets the ball in space, it's hard to get it off him.
I think Diarra is less needed for them than a distributor (d'agostino/pirlo, etc) , but he'll make them rock-solid defensively.
I have no idea why Arsenal weren't interested. They need a DM more than any other top club in Europe.