Base A flies x hours per year in an aircraft that costs y per hour.
Base B flies x+ hours per year in an aircraft that costs y+ per hour.
Option 1. Do nothing. Costs remain due to Base B flying rate.
Option 2. Close Base B. Unacceptable for operational and public perception reasons.
Option 3. Swap the aircraft around. Base B. Retains flying rate at a reduced cost, Base A retains flying rate at a higher but not as high cost. Equation now reads.....
Base A flies x hours per year in an aircraft that costs y+ per hour.
Base B flies x+ hours per year in an aircraft that costs y per hour.
It's called the laws of compensating reduction.
Simples