that's not what the people saying that Shane is the best are saying! It absolutely amazes me that people still don't understand simple logic and math. The shorter the race, the more chance a worse player has to win. The longer the race, the less chance the worse player has. How is this still not registering?
The fact that these world championships are races to 7, allows the worse player to have more of a statistical chance at winning. Hence, a very high variance. A much longer race, favors the better player, hence a low variance. If the world championships were races to 20 then Shane would win almost all of them at the moment because he is the best in the world.
What makes you so sure that Shane is actually the best player in the world? Yeah, races are too short in tournaments (although i don't think WPC is race to 7), and there aren't enough total tournaments, so the only defensible conclusion I see is that there's not enough data to tell.
In tournaments with all the world's best players, Shane doesn't have the best record. He might still be the best player, due to variance as you say. But so might about 20 other guys.