That's a myth. Latin America and the Caribbean are very poor, and the kids do not throw year round like the American kids do. Year round play requires lots of money for travel, coaching, equipment, etc., and the Latin America/Caribbean kids simply don't have it. More, they play soccer much of the year. Like Mariano Rivera, who was mainly a soccer player in his youth and didn't pitch until he was 20. Poor Mariano, he could have been a better pitcher if he had only played rear round as a youth, right?
Finally, there's a reason why a couple years ago when 35 MLB pitchers succumbed to Tommy John surgery, 34 of the 35 were born and raised in the American travel ball system. Only 1 was foreign born. Gee, I wonder why?
Keep on keeping on year round! Because you wouldn't want your kid to grow up to be a lousy pitcher like Mariano Rivera! LOL