American players are too Hollywood now. They've been getting their asses kissed and pampered since they were in High School.
Prospects are groomed to just secure the bag. They want to live a rappers lifestyle and be pretty rather than develop their craft or grind in the dirt.
It's like Rocky III when Rocky thought he could take Clubber Lang and Mick had to pull Rock aside and say You've gone too soft, he'll eat you alive.
That's why the trend is outwards. You can pay some overseas talent one third of a spoiled American player and get the same job done and more. Ya'll too Hollywood.