I disagree, Zidane is not over appreciated. Infact, I am one of those who think Zidane's performance took a downhill once he joined Real Madrid. Doing tricks in la liga is not like doing them in Serie A. In la liga there is not so much pressure on the legs like in Italy.
With Juve Zidane only score ~33 goals but he assisted 10000 goals

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I think over appreciated personale are: Emerson, Vieira, Ibrahomovic and CAPELLO..
Many where linking us winning the 04-05 stolen scudetto to Capello where actually it was team work that got us there.
Many were saying that our deffense is so strong because we have Emerson and Vieira where it was Cannavaro, Zambrotta and Buffon who were working their asses off. It was clear whenever Giannichedda got to play he out performed both the french and the brazillian.
And Ibra, well he seriously over appreciated by Capello and some fans. Ok he had a decent season where he scored alot (16 goals) BUT Del Piero who was subbed like crazy and did not get a proper playing time scored 17 goals.
I think us pulling off the 04-05 scudetto has alot to do with Del Piero getting back from injury and to his fitness not Ibra's performance.