Clayton Kershaw, LHP, Dodgers
No. 4 on 2008 Top 50
Kershaw is so good that he'd likely still be the highest-ranked pitcher on this list even if he were right-handed. His combination of size, mound presence and stuff was the best the Minors had to offer. The fact that he does it all from the left side is icing on a pretty good cake.
Kershaw, at age 19, was the best pitcher in the Midwest League and then seamlessly handled the jump to Double-A. His fastball-curve combination completely befuddled hitters in the lower levels of the Minors. Upon reaching the Southern league, he started to mix in a changeup, allowing him to finish second in the Minor Leagues in strikeouts per nine innings.
He can throw his pitches for strikes at any point in the count and aggressively goes after hitters. The jump to Jacksonville officially put Kershaw on the fast track in the Dodgers system and while they've had some cautionary tales with young arms getting hurt, it's not hard to envision Kershaw reaching Los Angeles before his listed ETA.