No system of play up front. They are clueless. This is something that even Allegri himself admitted that he was guilty of, but he didn't care. In his words, football is very simple: you build a solid, organised defense (of which we don't even have anyway LOL), and you leave the attackers to their own devices. In other words, they'll create something by themselves. This flawed ideology could not be more painfully clearer in this match.
Contrast our movement and behaviour in the final third to Napoli's. They are light years ahead in this department. How nice would it be to have just some form of identity out there.