People love a shiny young player because they're loaded with "upside" and no one has been burned by them before. The hype surrounding them also leaves them vulnerable to overdrafting.
The problem is, if enough people think a player is a "sleeper," then he is drafted earlier and earlier until you are paying for his best-case scenario. This is the case with the starting pitcher on this squad. He has been hyped to the level of making owners pay for his top potential, instead of his realistic expectations.
This young pitcher, and many other people on this list, have no upside left. If they perform to their highest potential, you get exactly what you paid. If they do anything less, then you end up with a bust, relative to the draft position.
Be wary of these players being taken far too early in drafts.