Key of success is defense and they are bulletproof. I would also say that Sampaoli did a bad preparation for the game. He is being outclassed by Zidane so far. Sevilla didn't create one serious chance.
they exaust opponent and then they hit them, if they are goal down, they will put 200 crosses in the box and one of them will finish on ramos or ronaldo´s head
There is not only one way to play good, Real system is pretty coherent, Zidane buildt a compact bloc capable of fast transition, which suits perfectly the profil of real players.
The only weak point of this system is it consume a lot of energy. Though it was solved thanks to a good bench allowing Zidane to rotate efficiently