international youth baseball question?

I've noticed as I was reviewing the participants for U-14, U-16 and U-18 international tournaments, teams such as the Dominican, Nicaragua and Colombia rarely participate or are substandard. These teams are considered baseball countries. Yet I've also noticed teams such as Argentina, Brazil, Guatemala and even Aruba recently were present. These countries have nascent baseball programs. One could argue that the former nations are poor, but the the latter are also poor nations. So what gives? Why doesn't the Dominican dominate? During the next WBC the Dominican will arguably have the most talented team, save the pitching staff.