Zidane is an exception to the rule, but he was schooled in tactics at the Lippi university. Usually top players don't make top coaches imho - because they would expect almost impossible things, especially in clubs with natural pressure. I can only imagine ADP, R9 or the likes showing a group of players (some even at Juve) how to do a certain move, take 3 players and score - just to be disappointed why no one is 'getting it'.
PP: On a sidenote, even Zidane seems to be performing better with top players, than average ones. I guess even with the whole world on their shoulders it makes for an easier communication of ideas and the ability to execute them on field.
One of the reasons I would like to have him here WHEN we have a top team, at least technically.