You're vastly underrating the level of talent playing overseas. Jeremy Tyler was a bigger prospect than both Melo and LiAngelo. He was ranked #1 PF in his class before he went to Israel. He got cut from his Israeli team, couldn't get playing time. He had to go to Japan to get playing time. Brandon Jennings only got to play 19 games in Italy (the season is 40 games, and he was healthy) and he was the #1 PG in his HS class. Teams overseas need you to contribute immediately, and if they don't show their worth immediately, they won't even play. These teams already have young domestic talent that they want to develop. Now they're bringing in two foreigners that need to develop. They will need to find a team that will actually play both guys, and be willing to develop them. That's going to be really hard.
You can also hire tutors overseas if you want.