As good as the US sporting system is in development sometimes it just can't cut it. I'll give you a good example. At the moment there are over 100 Australians playing in US college basketball. They are there because they offer what a lot of Americans don't and that's mental toughness, an attitude that is selfless rather than selfish and skills both as athletes and as citizens. Whilst American kids are thinking about contracts and how to spend them, Aussie kids are working on their fundamentals. Of my top 10 Aussies in the NCAA, 2 are on all academic All-star teams as well as their divisional All-Star 5's. The AIS is as good if not better than anything available in the US. If a person has the talent then they will be picked up and offered a scholarship to attend.
The big difference between Australia and the US isn't that they do it better, it's that they just do more of it. Here a regular joe footy player isn't offered state of the art facilities and scholarships, but in the US if you've got any amount of talent you'll still get a partial scholarship and utilise state of the art equipment. You'll still be the same average joe you were to begin with though. On a rare occasion someone might benefit from it, but if you weren't good enough to be noticed and driven to the top of the heap on raw talent to begin with then you're not likely to make it by either the US or the Aussie way.
Race has very little to do with why Pacific Islanders are good in sport, or why Koori's or African Americans make up large percentages in the sports they play. It all comes down to who wants it bad enough out of large numbers playing and that being dismissed as a genetic edge. Koori kids all grow up with a ball in their hand, there aren't many other avenues where society expects them to be an even chance at success like football. In any race if a large percentage of people are doing one activity you'll have a smaller percentage that are good at that activity and then only a few among those who will rise to the top of that heap. If as many Caucasian, African or Asian kids spent their free time living and breathing football then they too would boast similar population/participation ratios. Yeah race might then show small differences, but nowhere near what has been suggested on this thread. There's so much bollocks to this kind of sterotyping: Africans don't make good quarterbacks, black guys can't swim, Pacific Islanders are better at rugby, white guys can't jump, all blacks have rhythm, asians are better at math..
bollocks the lot.
If you've got the heart it doesn't matter what shape, size, colour or religion you are. Faster twitch fibres might help as will natural bulk but we're not talking about needing that 0.01 second edge nor are we talking about a naturally big guy running over the opposition when a proper diet and weight regimen can help most people to the same goals. If Australia was flooded with Africans it wouldn't mean diddly squat. England isn't exactly flooded with world class Ellery Hanley and Billy Boston clones now is it?