I don't think that it is necessarily a need for US trained managers - I just think that some fairly average Indians and Chinese middle managers working in the US have seen that they can leverage their 'American Experience' into a better job back home.
Rather than a reverse brain drain - it could just be the Dilbert principle.
The point is that there are fixed rules in Maths for what happens when you multiply 3x3 matrix by a 3x1 matrix and if this is even possible. Those should be enforced by the person writing the library's overloaded features not be left to the programmer to know which is the appropriate function to call.
Multiplying matrices is no more weird than multiplying a float by an int or a positive and negative number.
The statistic of people moving into senior management on moving 'home' suggests that companies in developing economies feel that they need American trained executives to compete with American companies.
So all this might mean is that middle managers in US companies are being automatically promoted into senior jobs in foreign companies because those companies feel insecure. This is great for the bank balance of those people but doesn't necessarily mean a great deal for the company.
It's also not a new phenomena - having a 'BtA' (Been to America) used to be almost a requirement for promotion in UK academia or medicine. It didn't lead to a huge amount of innovation in the NHS.
Rather than a reverse brain drain - it could just be the Dilbert principle.