Just because a player isn't as good as people make him out to be, it doesn't mean that he's not any good. Sometimes even the most inspirational players can't quite make the contribution that you expect from them. It might be down to injuries, whether major or small and niggling, tiredness, whether physical or mental, a lack of form, or just a good man-marker.
We make players out to be icons, but they're not. Del Piero's jsut another player, a little better than most, but not invincible, not unstoppable. How many players in Europe made the contribution of Nedved to their team last season? Two? Three?