Everyone specifies certain players as "prospects." These are players that have shown major talent at a young age.
"Prospects" have busted out of the gates early in their lives, in their careers, and have put up spectacular numbers against players not nearly of their caliber. That's my problem. These players are usually tearing up leagues against players who are just budding, or maybe won't even pan out. Some players work, others don't.
As they work their way up the minor league team, you really get a chance to prove themselves. They should stay consistent as they move up the chain, with a bit of time for them to adjust to their respective leagues and it's talent. I would much rather trade away a "could be" for an established player, any day.
Guys like Fernando Martinez, Mike Carp, and Jon Niese could be great. They could be something special. They could also be the next Alex Escobar. You just never know. I side with the thought to trade away these players for ones you know are established in the majors, know they can hit, field, and handle the pressure.
I'd much rather have a proven talent on my team over a kid who tears up the Eastern League against pitchers who will never even taste the big stage. Obviously, you need to hang on to some prospects, but not every player in your minor leagues is going to be a star. It's all a crapshoot, and the GM's will feel the heat if they deal the wrong guy, but it's all to up to chance.