"Among blacks who earn professional degrees, the impact on their chances of finding a job is nearly one-and-a-half times greater than it is for whites who earn the same degrees. In addition, African-Americans who have bachelor’s degrees earn $10,000 more a year than those who don’t have a bachelor’s, compared to white men, who earn just $6,100 more than they would if they didn’t have a bachelor’s. The value of a graduate degree is even greater for African-American men. Those who have advanced degrees make $21,000 more per year than grads with bachelor’s degrees while white men with advanced degrees make just $15,100 more, according to BLS and Census data and analysis by a group at the College Board."
And your cited source failed to use simple common sense as to why a white high school graduate might be more attractive to a hiring manager than a black college graduate for some jobs! If it's not a good job then a college graduate might take it for the short term but will give it up as soon as a better one becomes available...a high school drop out may not have the option to take another job simply because they don't have the required degrees.