One of the main driving factors behind the 'main base' policy was consumption of airframe hours. Also, returning loads from theatre(s) and delivering to outlying bases often requires a crew change at Lyneham, using 2 crews for 1 task. Not very efficient, from 2 Gp or the Stn's point of view.
With regards to the rugby team, you'll most likely find that the task used MCT hours - giving up our own (scarce) training time - incurring costs that would have occurred anyway. Not that I agree with using our precious trg hours in this fashion, but that's another issue.
16B