In baseball especially, it's difficult to project how a prospect will handle the transition from Minor League ball to the Major League level.
It's a game of adjustments; opposing players will identify a new guy's weaknesses and exploit them. If a young professional refuses to make the necessary improvements--or is simply unable to--than he's unlikely to last a full season.
Plenty of those who struggle at the onset of their MLB careers turn themselves into serviceable players, but most of the league's elite shine from the very start.
Just as in the American League edition of this article, I'm ranking my top 10 candidates for Rookie of the Year.
*Note: I only considered rookies with 50+ innings pitched or 300+ plate appearances.