Don, Cassano did nothing, except picking up an immediate yellow card. The entire forward line was starved so nobody up front did anything.
Holdon, Del Piero plays because he is the best Italy has in that position. Why did England bring Beckham with a broken foot to WC2002? Because Beckham at 75% was better than anything else England could offer. Del Piero at 75% is better than Italy can offer at present, and DP's performance was as good as any forward player in the team today. Vieri, Camoranesi, Totti, DP, Fiore, and Cassano all did exactly the same, which was zero.