Truth is, there are both multi sport and specialization athletes that have made it to the highest level of baseball. I don't see one way being any better or worse than the other way.
i actually like to see kids participate in all the sports, if that is what they enjoy. However, there are a large number of Latin players in the Big Leagues and nearly all of them specialized in one sport.
To me there is nothing wrong with either way. I do believe that specializing in one sport shouldn't include actual competition year around. This is especially true for pitchers. However things like fielding and hitting are something the more you do the better you get at it. There are a lot of Latin shortstops in the Major Leagues. Is that because they are better athletes than those here in the states? I think it is because that 16 year old from the Dominican has simply fielded twice as many ground balls as the 16 year old here in the United States.
It is amazing how many professional baseball pitchers and players were Quarter Backs in high school.