It is very clear that riot wants certain champions to be played at worlds.

There is no other explanation for riot's balancing decisions these past few patches. Riven was just nerfed for her extreme dominance yet they are buffing her back. Graves is getting buffs even though he doesn't need it. Vayne is getting buffed for no reason. The veigar buffs on pbe is disgusting, 6.6 second cooldown aoe stun late game.