My son's travel ball baseball team only has one Asian player. The team is based in Irvine but only 3 are from city of Irvine though.
My other kid told me that many Asian kids in high school quit sport to study for SAT or boost GPA for college in jr and sr years. Also I've seen Asian parents forcing kids to quit sports.
It has to do with physical size and strength. Also there are a lot more white and black kids with parents who played sports in their youth and even high school and college level than most immigrant Asian-American parents. What you get through gene and learn from watching your parents do are two biggest factors in kids' developing interest in sports (same goes to most of other occupations).
The prime examples are Steph Curry, Caly Thompson, and Kobe Bryant, all are among the greatest NBA players with fathers who were pretty dam good pro players themselves... May be in 25 to 30 years, Jeremy Lin or Yao Ming's sons could make it to NBA...
My point is, even though we see more Asian kids getting involved in sports and getting better physically, they just can't complete with bigger, stronger, and taller counter parts (just yet). Asian parents put more emphasis on academics than sports, which is nothing wrong, but the dog that you feed more will get grow stronger...