Aaron Crow, RHP, Kansas City Royals
Drafted in the first round by the Royals in 2009, former University of Missouri ace Aaron Crow was considered a very advanced pitcher who could make the majors within two years. Alas, 2010 did not go well: he posted a 5.66 ERA with a 90/59 K/BB and 130 hits allowed in 120 innings for Double-A Arkansas, leading to a demotion to High-A which resulted in an even worse 5.93 ERA, though his K/BB was good at 53/6 in 44 innings. Crow came into 2011 spring training as a big question-mark, but he looked like a completely different pitcher, forced his way onto the roster, and has been excellent in major league action so far (zero runs allowed in his first 7.2 innings, with a 9/2 K/BB).
What's the difference between '10 and ‘11? Crow's fastball ranges between 93 and 97 MPH, just as it did last year. His slider is also effective, but he had problems with his changeup in ‘10, as well as mechanical flaws that hampered his command. Used as a reliever this year, he's been able to concentrate on the fastball/slider combo, and has kept his mechanics more consistent, getting his command back to where it was in college. Crow has the stuff to be a major league closer, and if he continues to throw strikes as he has this year, he'll eventually get the opportunity, though it would require an injury or trade involving Joakim Soria for that to happen this year.