from what ive experienced, so its not accurate at all, just my view point on it
try hitting 10 level 10's, you will have a steady stream of max attack damage
then try hitting 10 level 25-30's and the max damage will vary due to the opponents increased resistance.
my theory is that resistance does this to the damage range taken (crude example btw. 150dmg-450dmg * 0.84= new damage range 126dmg-378dmg)
and the attackers accuracy/dexterity/strength tries to counter that damage decreasing effect.
It's how I see the system working