Your memory is a little off. De Rossi got a red card for elbowing someone and was banned up to the final where he came in in the second half and converted a PK.
Also, USA only managed to score because Zaccardo scored in his own net. He literally did not play one more minute of that tournament and the guy who replaced him was the guy who drew the PK against Australia, scored the winning goal against Germany and scored the winning PK against France in the shootout
So basically, USA was the only team who managed to score on Italy in regular play and that lead to the chain of events that allowed Italy to win the WC. Thanks