Perhaps to a minority of delusional fans here but in Marchisio's case, being Italian and a youth product has done more good than bad. It pretty much saved his Juve career when he was a mediocre player. The club would not have been that patient towards a foreign mediocre player.
Gotta disagree that he didn't deserve his role in the team at times. Even though he wasn't always a WC midfielder, he still was good enough to start for the team at the time.