I think this is a fair topic as long as people keep it reasonable.
To be honest, this is not a black vs. white topic, which some people will inevitably try to take. It is a white vs. white topic. I think the real question is, why are European and South American "white" players able to make it to the NBA and have a strong impact and our white, and even latin american, players from the US tend not to make it in the same way.
Non-American Players with big impact - Dirk, Manu, Gasol Brothers, Bargnani, Nash, Scola, Rubio (perhaps), etc.
Really Kevin Love, maybe Fredette one day, are the only ones in the league right now that are in that category. And Stiemsa is close...

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We have plenty of solid "white" players in college but it just does not translate into the NBA. Does this have more to do with players in other country's going pro earlier or perhaps getting more opportunities because there is less competition or are our elite white athletes going into other sports (swimming, football, volleyball, etc.).
I do know that GMs go gaga over the unknown/potential factor over the white athletes in Europe, and some of our guys get overshadowed because of this and don't even get drafted eventhough they had solid college showings. If you miss out on getting drafted, the road to the NBA gets that much harder. Sometimes it comes down to opportunity and GMs tend to give average international players more opportunities than american born players to play in the league and grow with other professionals.