MAN's USA figures are not spectacular at times, and that's fed by various regions. NCL could not hold down a service, neither would LBA, or an alternative in similar area.
Just like MAN cant fill services only LHR can, sometimes you have to accept what you are.
The north can only sustain limited long haul, and that's catered for by MAN no matter how frustrating that maybe for Yorkshire, or Merseyside etc. That will never change now, that boat sailed long ago.