He's so good and so powerful that he wrestles as if he were bored and as if he didn't need to pay much attention because the challenge is not enough.
When the match reaches its climax, which is precisely when the wrestlers get more serious, he does the opposite and puts his hands in his pockets to imply that he is overconfident and can afford not to use them because his opponent has not proven to be any threat. It's as if he's so good that he doesn't need to use his true abilities, and as if he doesn't want to use his full power.