Some months ago, I read an article suggesting that the primary problem facing NAM's was a lack of Patience, not a lack of any other trait (IQ, conscientiousness, etc.). In particular, the NAMs suffered a special unwillingness to take shit from their bosses. And of course, it's well known to my regular readers that I think that patience (willingness to defer gratification) is the uber-trait, beating out IQ by a fair margin.
Upon discussing this with my wife...she pointed out that we have a pretty solid model of internal/mental resources as limited. Kahneman's recent book reminded us that concentration is a finite, depleteable resource. Similarly, a couple days ago John Goodman linked to a study showing willpower is measureable in blood glycogen levels or some such (the Aretae theory of how sufficient sleep positively impacts weight loss relies heavily on this linkage)
Suppose for a moment (actually, I'm asserting that this is true) that on average, NAMs get more shit in a given day before they get to work than do whites/Asians. If this is true, then you should expect that a the characteristics of our society would make it so an average NAM would have a lower tolerance for boss-, or customer- bullshit than an all-aspects equivalent White who hadn't suffered the same amount of crap on the way to work. If one adds in that many folks also give MORE shit to the NAM at work...you've built a relatively unsustainable position.
Same results (lower tolerance for BS, with massive negatives on job-results), different explanatory structure.