This effect could be explained by the international standing of the university without recourse to inverse-nationalist bias. A Stanford degree is better for an

This effect could be explained by the international standing of the university without recourse to inverse-nationalist bias. A Stanford degree is better for an Italian than a Sapienza Rome degree. But a Cambridge degree is better for an American than a Georgia Tech degree. Since the US has lots of top-tier universities, you see lots of American-trained professors in European schools.