Maybe I just haven't been paying attention but I don't think we can tell enough about the coaching dynamics to say this guy or that guy is the problem.
(For instance Gulutzan is the special teams guy but apparently Sullivan is responsible for the defence and this affects who is available for the power play etc.
I will say this, Sullivan looked bad stepping in for Torts during his suspension but the way this team was going I don't know if Scotty Bowman himself could have turned things around.)
But if you just want heads to roll without cleaning house, I'd say fire Sullivan and make Torts deal with someone else next year.
Hell, if they're as inseparable as people say, fire Sullivan and maybe Torts quits and saves you having to pay him the next four years.