Killer used to mean you were in the top 10% of active players (roughly).
Now it means you are in the top 60% of all players. (after considering “bonus points”)
So yeah, in KILLER rank you will find people of ALL different skill. Form Untouchable Jagos, to Lucky combo-assist rushdown players who just happen to make correct guesses.
I REALLY think they will make a new ranked system soon. I know i would be happy, even if it means being stuck at “button masher” again.