Let them play, if others can't win is technically not the staff's fault. There's no such thing as negative benefits for staff members, just like you working in a hospital as a Doctor but then you suffer *insert* disease and you're not allowed to receive treatment cause you're a staff.
It just doesn't make sense.
If the staff keeps winning perhaps cause of rigging, punish them individually and not affect every others.
Only apply to staffs with VIP