I think 4-3-3 could actually work well in Serie A too, providing we had actual wingers.
Teams exploit us in Europe by creating 2v1 situations on the flank, yes? They exploit our lack of witdh.
Look around the league. What does nearly every other team lack? Width.
We could do a lot of exploiting of our own with the correct personnel. I mean, we already do use our wing-backs a hell of a lot. We could work wonders in Italy with 2 top quality wingers going up against these makeshift wing-backs.
I'd hate to be a left wing back playing in a 3-5-2 if my direct opposition was Lichtsteiner and Menez for example.