Blogger Matt Perez, expanding on previous work by Victor Wang and Scott McKinney, analyzed the major league success rate of Baseball America's top 100 prospects from 1990-2006. He found that 70 percent of those prospects "fail" by his empirical criteria but that players high in the BA rankings do well. Players ranked in the top 20 go on to be successful in the big leagues nearly half of the time, while those ranked from 21 to 60 become successful about a quarter of the time and those ranked 61 to 100 make it about 20 percent of the time.
Obviously projecting major-league success for young prospects is difficult to do. Baseball America’s John Manuel notes that the Braves acquired a lot of “high-ceiling talent” but took on some risk with several raw arms and the 30-year old Olivera.
But with nine Braves prospects now having appeared in the Baseball America Top 100 at some point, the franchise can probably count on perhaps four or five of of them becoming (or being traded for) solid major league players. That's a good foundation for the future.