Baseball had been king in Puerto Rico for the better part of a century. But now the Puerto Rico Winter League is all but dead. There were only 20 players from Puerto Rico on major league rosters last Opening Day. What happened? According to the sources for this New York Times article it was the imposition of the draft to Puerto Rico in 1990:
No one here disputes the diminished stature of baseball in Puerto Rico, and most agree on the culprit: the decision by Major League Baseball, in 1990, to include Puerto Rico, a commonwealth of the United States, in its First-Year Player Draft. This means Puerto Rican players must wait until they turn 18 to enter the major leagues, and then they are going up against players from the United States and Canada in the draft. Also, perhaps more important, major league teams have less incentive to cultivate talent in Puerto Rico since those players may end up with another team through the draft.
Major League Baseball — specifically Sandy Alderson, who is quoted in the article — notes that Puerto Rico’s socioeconomic situation has a lot to do with it too. It’s not as poor a place as Venezuela and the Dominican Republic, so there is less of an incentive for hungry young kids to play their way off the island. At the same time, it’s not so well off that it can support an amateur talent development structure like you see in the baseball hotbeds of the United States like in California, Texas and Florida.
Of course, it’s not like Puerto Rico’s economy suddenly burst out and minimized the importance of baseball in 1990. And 1990 seems to be a pretty clear demarcation between the time when the island was bursting with young baseball players and now, when it is clearly not.