We need a finisher on the side of a support striker. But if Ciro wants to maintain 4-2-3-1 formation without one, Amauri, who's a more physical player, can do better as a lone striker in my opinion. Trezeguet is accustomed to have a partner in attack who will absorb opponent's centre-backs attention and eventually create him direct chances to score. As soon as Del Piero is back, we can go back to 4-3-1-2 with Trez as a finisher being the best option at the moment.