In 4-3-3 Mirko can be replaced with a winger. But that's system on paper. His goals won't be missed because...well...he scored only two.
But it will be really hard to replace his intelligence, taking on defenses, having the guts to take the ball and try to do something, his smart movement.
The only one who can realistically replace those positives in Vucinic's game is Del Piero, but not in a 4-3-3.
Pirlo and Vucinic are essential to our play, as hard as it is to notice it and as easy as it is to notice their flaws. But they are really important. Sucks to lose either of those two and I'm not sure how can they be replaced. In our case now, we must find a way to replace Vucinic and I don't know which one between Del Piero, Quag, Elia, Esti, Krasic or Giac is the correct choice.