I'll add to what Seth said. Late bloomers can sometimes become better players than the guys who sign at 16. But they have a shorter runway. So the odds of a 16 year old are just higher than a 20 year old, all things considered. Also, if they sign at 16, scouts really like them. If they don't sign until they're 20, chances are, they have some flaw preventing the scouts from recommending them. For me, the main thing about age/performance is ensuring that the player is ready to contribute in the MLB in his peak years--26-30. Again, the odds of a guy being able to do that are higher if he signs in his teens. But guys can sometimes beat those odds. On the other hand, it can be challenging signing 16 year olds who are slow to develop. Kepler and Polanco, for example, are great prospects. But they each took an extra year in rookie ball to develop. And they will use their first option this year. That means they must make the major leagues by 2017. Because they will most likely end the year at Fort Myers, they cannot afford injuries or other things that might delay them if we move them along a year at at time. As Seth said, if Abreu makes it to E-ton this year as a 20-year-old, he could make it to Cedar Rapids as a 21 year old, Fort Myers at 22, New Britain at 23 and Rochester at 24. At that point, if he's still a prospect, he would use his fist option, and could be available to the big club for much of his prime years. He just needs a lot of luck at this point, which is why he isn't in the prospect rankings.