Actually his performance in the wc 98 WAS already exaggerated by 1998 itself. He was suspended for 2 and a half games, first game they played vs an average South Africa, he did shit vs Italy and was meh vs Croatia.
I also believe his 06 performance was pretty overrated, the ones that saved his ass were Vieira and Thuram who put on a performance in the last group stage game where he was suspended, and which qualified France to the next round. He was so so vs Spain, but the goal was cool, specially cause Spanish media made comments about retiring him. He was out of this world vs Brazil (which is what everyone remembers), and average in the remaining two games, ffs, he got himself send off for something so dumb in the final (even if we all would have wanted to head butt Materazzi, there's a moment and a place, a hard intense WC Final is not the moment), he ended up fucking his team over.
But Zidane was amazing in the Euro 2000, one of the best performances I've seen from a player. And was amazing with Juventus. Overrated with RM, or maybe not his fault, but he was put in a team with so little balance it exposed him so much, well his first season with Madrid was great too to be fair (surprise surprise, Madrid had a balanced team then), obviously though he looked flashier in La Liga than in Serie A.
I dunno. I go back and forth on this. Around 2006 I was convinced he deserved his place in the top 5 ever, looking back, I'm not all that sure anymore. I do think he was better than Rui, but regardless of anything, he is one of the greatest ever, maybe not top 5, but that ends up being pretty subjective.