We know there are big disparities of academic success by ethnic group (cf the whole harvard discrimination against asians controversy), and there are also big c

We know there are big disparities of academic success by ethnic group (cf the whole harvard discrimination against asians controversy), and there are also big concentrations of patronyms by ethnic groups (or at the minimum first letters that are more common in one part of the world than another). And on top of that if the university itself discriminates against certain ethnic groups in its recruitment it will reinforce this bias (like if asians students require better grades to get in, it is unsurprising those students that get in perform better than the rest). That would be my best guess for a rationale behind that result.