Whether it's Quinn or Ruff or the players, this team is definitely going nowhere until they figure out how to play defense.
Now, it's probably all 3...you can't play such a passive defensive scheme in the NHL these days, it gives the other team too much time and space to do whatever they want. You have to pressure the puck and the rangers don't do that by design. This is a conscious decision by Ruff and Quinn. Beyond that, if Ruff is coaching the D, they still seem to have trouble in their own zone with assignments and gaps and positioning. Beyond that, the players often take too many risks that are resulting in counter attack goals against.
e: also, was Kakko benched because of the offensive zone penalty he took in the third? Seems a bit harsh...