Yes Zidane is one if the most overrated players of all time.
If you check his stats you would actually be surprised. A full season of 5 goals and 4 assists was his standard. Thing is most people do not watch regular league games but only the big ones and therefore remember WC 98 final, CH league 2002 final and WC 2006. However, even his international career is overrated a little. When we look at the tournaments:
Euro 96: non factor
WC 98: good Game against Saudi-Arabia, red card against Denmark, non factor until the final. In the vote for best player of the tournament (which is done before the final), he finishes 5th, not even the best French player (behind Henry). Then in the final he scores twice and out of the sudden he wins the World player of the year award.
Euro 2000: Some good games, invisible in the final but overall a good tournament.
WC 2002: Did nothing (literally)
Euro 2004: good game against England. Overall nothing special.
WC 2006: maybe his best tournament. Should have won the title here, better than in 98.
Let’s then come to his international club finals:
UEFA Cup 96: non factor in both games
Champions League 97: non factor
Champions League 98: non factor
Champions League 2002: Great Game
UEFA Super Cup 96: non factor
UEFA Super Cup 2002: Non factor
Intercontinental Cup 96: non factor
Intercontinental Cup 2002: non factor
So basically Zidanes whole reputation as one of the best players of all time is built on three good performances in finales (and some additional good semis and quarters). Not bad, but to be viewed as a GOAT candidate??