Cheng explains it thusly: "Monsters have a 'CC resistance' that is stored on a per-monster basis. The CC resistance starts at 0%. For every one second CC that is applied to the monster, the monster receives 10% CC resistance. Monsters lose 10% of their CC resistance every second that they are not CC'd. Elite monster CC resistance is capped at the current reduction values already active for Elites."
He says that after the change, "near-infinite CC strategies will work," making the player feel powerful while not unbalancing the game.