Think about it. just like matsuri and arena, the event requires people to register to effectively match based on it's criteria (level first then power, which we all know is flawed). If the top bracket needs more people, it would grab people down below. Leveing also causes this placing and eventually you be moved back if someone else levels with a much higher power than yours, which happens to me a lot. Sometimes, I get bumped down to a bracket that is almost the same as my typical bracket and it is usually due to registration. Brackets should be more stable once we have more people reaching the max level.