Could it be that they are being screened out based on "intended major"? Attending Berkeley for my BA, where 20-30% of the school was Asian or Asian American, it seemed like a huge percentage of the Asian students were solely set on STEM and Bioscience majors. Maybe admissions realize that if they want to keep the Humanities, Arts and Social science depts around they need to admit fewer Asians.
I believe there is a similar story used in statistics courses (based on a true story) of a possible case of gender discrimination. The university (or universities) basically appeared to be discriminating against females (maybe lower overall acceptance or higher scores). Further analysis shoed that females were applying to more competitive majors. I wouldn't be too surprised if something similar was going on here.
