Foul disparities are, generally speaking, mostly a factor of athleticism rating, defensive rating, and IQ. Secondary factors include types of set (press fouls more than zone, for example), fatigue (can be more than a secondary factor when it’s a real problem, but it’s only a real problem for a minute or two at a time in most games), and defensive setting (minor, and speculative - the idea that negative settings foul more may just be a forum fact).