when the ufc releases these numbers, like duffman's 8+8, they have to understand that most will take the figures literally. those figures are going to be reported, and the company is going to be presumed as cheap. why not disclose other payments then?
i'm inclined to believe that 'behind the scenes' bonuses aren't all they're cracked up to be. the ufc doesn't seem to have a problem dealing in mostly paltry sums (relative to what we think getting one's head caved in should be worth), so lets be honest, they're not going above and beyond with undisclosed payments. fotn/sub/ko bonuses aside, they could throw an 8+8 guy an extra couple of grand and he'll be sweet and say the right things, but the sub total is still very low. dana can say 'well, we give these guys a bunch of money you don't know about' which technically may be true, but it's all relative.
now, these guys know what they're signing up for, and their money is noone elses business really. but the reality is, a vast majority of the ufc roster will be criminally underpaid and therefore should be eager to put on a show to be in with a chance of fotn/sub/ko, and that's just how the ufc wants it.