Just to clear things out:
Del Piero did not score a goal IN THE SERIE A from an open play until the end of the season when he scored a header after pessotto's cross against Buffon when he was at Parma. Never the less he did score in the eufa cup that season.
The next two seasons were good. Not upto the level before the injury but were Very good. The whole team though was not well organised thanks to brilliance management by the one and only Carlo Ancelloti. When Sir Lippi came back the team showed its worth again, as did Del Piero he was crucial for Juve's campaign two win the scudetto two times in a raw whether it was by scoring assisting or leading on and off the pitch. In 03-04 he got a couple muscle injury that put him away for quite awhile. Infact, he her returned back late in the season. Being away from football he gained weight (obviously). Early in the season after (last season) he got injured after the Lecce match, which was soked with rain and he scored a goal as well.
Afterwards he returned back to his best. Was crucial for Juve to win the scudetto and now he is curcial on all competitions. Infact, even on Coppa italia which we did not lose until he stopped playing at it (the Roma games).
This season is very good for Del Piero, but saying that he did not show up for 5 years after injury is just plain nonsense.
Zlatan is a fatansticly capable player. In my opinion his problme is not physical as it was with DP after injury, it is mental. He has to get his head straight to play as he used to do.
I did not watch the Juve V Lecce game, but for the Inter match he was good and in the Messina match he was terrific. If he is having a dip in his performance I think he should be benched for him to get his head straight. But personally, I don't think he is having a dip. He played well in the past games, he has to concetrate more though.
I do think that Del Piero is the most inform forward at the moment.