NK only loses -1 elo if they lose
They get a lot when they win.
However, NK wins don't happen as often as others.
I propose that NK gain elo based on how many people that they kill.
If a WW kills 0 people before they get hung/killed - they lose -1 elo.
If they manage to kill 1 person, they earn 1 elo.
If they kill 5 people, they earn 5.
If they win, they get a win elo.
This would encourage nk roles to stay in the game an actively participate.