I don't think he ever was a lock to be the next great...he had this one great season with Bordeaux the year he was on loan from Milan, when nobody really expected anything of him, then he crumbled under pressure when put on the bigger stage (ie with France). To be fair, he got hurt a lot too. My inner conspiracy theorist says he came back to earth once the effects of the 'roids/EPO therapy the Milan doctors administer wore off.

people did greatly overreact to that very goal, though. Zinedine was scoring one of those every two weeks or so, just getting one doesn't make you the next.