By my calculations, the team is 57% non-Hispanic white (13.0 players), 33% black (7.5), and 11% Hispanic (2.5).
This pattern is not all that dissimilar to other American professional team sports where blacks and mulattos are over-represented and Indios and mestizos are underrepresented, even though Mexicans and Central Americans have a much stronger soccer culture than African-Americans.
I'm not going to pretend I've got fully scoped out the latest team of 23 players that's just been announced (e.g., veteran World Cup star Clint Dempsey looks kinda black, but that never seems to come up in articles featuring his parents), so I'll defer to your expertise in the comments. So far, I can say that among the three Spanish-surnamed players, Omar Gonzales is of Mexican ancestry (and is 6'5"), Nick Rimando is half-Mexican, half-Filipino, and Alejandro Bedoya is descended from a couple of generations of Colombian soccer players.
The U.S. squad often gets praised by other World Cup coaches for its athleticism. Its results in the World Cup are usually okay but not stellar, about as good as Mexico's.