I won't be amongst those that galvanise things up, but having special players like Cristiano Ronaldo, Gareth Bale, Toni Kroos, Casemiro and probably Luka Modric helped him win all that. This is the reason why he's rebuffed all talks of managing another side. The French national team is the only side he'll be willing to manage again asides that, it's a big no no for him. That same season he won the Champions League Competition last, he was so poor in La Liga he had to resign immediately the Champions League was lifted.
But you just failed to acknowledge that he was a genius with that squad and he knew perfectly how to manage them. You think it's an easy thing managing players like Ronaldo, Bale, Ramos, Toni, Modric in one team. You forget to add that when a team has too many stars in the team it becomes a problem. Again, the question is, where all these players not in the team before he took over? The answer is yes, but did they dominate Europe for three consecutive seasons without Zidane, the answer is no. You should give Zidane the credit he deserves.