Bison: I witness the same thing here in Mexico. Blacks, Hawaiians, Orientals, and Hispanics have their genetics rooted in the warmer climes. As a generalization, kids from warmer climes tend to mature earlier than kids from Northern European stock which come from colder climates. Germans, Danes, Sweeds, Russians, Irish, etc. tend to mature later than the first group.
While the maturity may not be visible externally until adolescence, they tend to have the edge in eye-hand coordination, quick reflexes, strength, and some of the other qualities generally listed as attributes associated with innate ability.
So as the Northern European kids mature they pass some of the earlier bloomers in other attributes such as height, etc. Now all of this has to do with generalities so dont get your shorts in a bunch citing particular players.
As a group, black kids are stronger as are Hisspanic kids but as a group white kids catch up. Some black kids are taller as are some white kids but black kids have a different anatomy to their fast twitch muscular fibers making them quicker and faster. So black kids tend to excell in track, especially sprints. But white kids have the edge in anerobic endeavors and do better overall in wrestling and long distance running.
Certainly one must consider preferences in sport selection where kids see success stories in endeavors that they are good in. Financial considerations also come into play with hockey and swimming.
Many factors go into the mix and one of them is anatomical differences. Another is heredity and age of maturation. Blue eyed guys seem to have an edge in pitching whereas brown eyed players do better in hitting.
I imagine that there will be some that take offense to the generalizations noted above. Oh well. I never was P.C.