I have a lot of respect for Mike, but this sounds like a scientific question, and that's not a scientific answer.
To state the obvious, if I used a much bigger ball, at the extreme, one with a larger diameter than the hole, the percentage would go down. So what is the optimum size? Is it larger than the current men's ball? It would be an astounding coincidence if the arbitrarily chosen size of the ball and rim happened to be the optimum size.
Or is weight more important than size (Careful, don't go there....)
A good scientific test would use balls of varying size and weights. It would be easy to make a women's size ball the same weight as the men's ball, to see if Mike's emphasis on weight is key.
The main problem with going to Mythbusters is that they like to blow up stuff, and this doesn't quite have a same appeal as the
JATO myth.