The link was clear enough for those who are prone to objectivuty. For those who just won't accept Blacks as equals there is always something to pick at. If the link was not good enough for you, there are hundreds more on the same topic saying the same thing in different words.
I'm not sure green carders are the immigrants mentioned in the article.
I did notice a reference to the American born progeny of African immigrants who wouldn't need a green card since they are citizens. Yet, the inference was that they too, despite superior academic achievements, were among the underemployed.
I'm a bit chagrined by your reference to bright Nigerian immigrants as the "cream of the crop" in their country as if to devalue their achievments here.That's sort of a veiled put down. You seem to have a mental block that won't allow you to see them as the cream of the crop in the diverse USA. Too bad...the facts are public...
Before you can conclude that, you have to show some reasonable proof that the immigrants referenced in the article are mostly on visas. The word immigrant can also be applied to those who have attained citizenship.
You claim to have read the links I provided, yet you missed some of the most important data indicating that
Blacks and hispanics are graduating from tech scools at twice the rate they are being hired.
You are falling behind the times..join the NAACP or something...that might be of some value in helping you to understand. some of your darker fellow Americans.