It could be the (unreported) fitness, or the contract negotiation. Either way, I don't think Ranieri is to be blamed.. I know the man's not a genius but he's definitely not the kind of coach who wouldn't give a chance to a talented youngster whenever he can.
Let's just see what happens vs Cagliari.
I am pretty interested in the contract talks too - what is Gio demanding? The boy's a massive talent and we definitely should keep him but I hope it's not a case of him demanding too much - he's talented yes but talent alone doesn't make you a champion, plus he hasn't exactly proved anything in a Juve jersey in a serie a game/CL. I'm not a big fan of these things, I think if you're only entitled to expensive contracts if you've given something back to the team.
Gio doesn't seem to be that conceited though, so here's hoping it's something else, maybe he just wants to ensure that he's part of Ranieri's plans this season.