I think around 80% it is due to a lifetime of hard work in a perfect environment (FC Barcelona's Academy) surrounded by the best people in the game. The other 20% may come from his psychological abilities, being able to reach very high levels of concentration at peak moments. Notice that he is not a very active and working player throughout the whole match, instead he shines through certain moments.

Some people also related this to the Asperger's Syndrome. http://www.reddit.com/r/aspergers/comments/1m17yp/alltime_gr...