I think it has to do with fights as they are on the contract. Somewhere is the link to how TUF fighters contracts go.
Like Griffins first fight was 10k, second fight 14k, third fight 16k, or whatever numbers and on an on. So if for some freakish reason he fought chuck at fight 3, he'd still only make 16K.
Does that make sense? I don't think the salaries are on a per fight basis, I think it goes along with whatever their contract states for that specific fight (most UFC fighters are not on fight-to-fight contracts.) If the fight is really good they make up for it elsewhere. Arlovski's fight was way up there because he is probably still under teh same contract renewal when he was champ, get me?