If you don't have enough staff buildings and equipment, service levels drop, this means the organisation just exists to "fire fight" preventative care gets forgotten... so timely interventions do not happen, the patient either dies or the treatment becomes urgent/more complex/expensive.
This isn't helped by every September, the govt throws 2 billion etc at the NHS for "winter pressures" this money just gets wasted, the NHS doubtless needs reform but it also needs to funded, per head of population, far more and demand has to be reduced through better public health, one thing would be for us all to eat less and move more!!
Either way, increasing retention levels through better pay is at least a start in trying to reverse the recent trends.