I was sitting at Tropicana Field the other day with my sons watching the Rays take on the Astros. Tampa Bay is a team with a lot of great young talent acquired through the draft: Longoria, Upton, Crawford.
A few years ago, San Diego Padres GM Kevin Towers was nice enough to let me in their draft room on draft day. Baseball's draft is considerably more complex than the NBA draft. A player's "signability" is a major factor with players not only in high school and college, but Latin America and Asia, as well.
A team's regional scouts make their detailed reports; then "cross-checkers" have to give strong opinions on each prospective draftee. Finally, the GM must have faith in his staff before orchestrating the the whole thing. The result is that there are many more gambles in the MLB draft than the NBA draft.
NBA teams might say they're considering so-and-so as a "project," but there's still a good chance that player could log minutes in NBA games over the next season or two. In baseball, even strong prospects might not reach the Majors for several years as they develop.
Baseball teams carefully develop their players by bringing them up through their minor league system -- Rookie League, Instructional League, Class A, and so on. They carefully watch their prospects along the way, meticulously tracking their progress.
After years of a loose affiliation with the old Continental Basketball Association, the NBA's D-League is pro basketball's more formal attempt at a minor league system, though it's no where near the level of complexity of baseball. As NBA teams begin to replicate what the Lakers have done and own their D-League affiliate franchise, you'll begin to see more players stay in the States (versus heading overseas to play). You'll also see more "bubble" players reach the NBA more quickly as their NBA clubs help them along.