A draft could be part of it, but other things are more important. More money in Latin America in general for instance. Why is only $10,000 exempt from the signing pool in Latin America where that number is $150,000 in the draft? Why have the international pools increased more slowly than the draft pools?
I'd push the international signing age back a year or at least 6 months. Then also think about ways to make velocity a little less important in general in the game. An international draft might help a bit too, but it is like the 4th or 5th more important thing they can do. Pushing the signing age back and providing some more youth resources would help more.