It has been explained before. Their culture considers gaming to be a legit career, and thus people are encouraged to really strive to excel at it. They have much higher standards for how they practice, they do not televise their strategies, and they work very hard to make sure their entire team is so well coordinated they don't even need to speak to know what another member would do in any situation. They make sure they know how every fight will go down, what spells will be used when, and how to create a situation that benefits their team way better than both NA and EU teams do.