Royals Prospect Review: Aaron Crow

Entering 2011, the Royals broke camp with a handful of rookies in the bullpen.

As a Rule 5 pick, Nathan Adcock had to stay on the 25 man roster or be returned to Pittsburgh. Tim Collins, after rolling through Triple A, looked like a lock early in spring training, and Jeremy Jeffress, acquired in the Zack Greinke deal, had pitched capably for the Brewers for 10 innings in 2010.

A surprising member of that rookie bullpen crew was Aaron Crow.

Yes, Crow was the Royals first round pick in 2009, but after a 2010 where he was demoted from Double A to High A, it didn’t seem like he’d be anywhere higher than Triple A to regain his footing.

After a strong spring training where he struck out 11 batters in 13.1 innings and gave up just three runs, he made the team. On opening day, he made his major league debut, striking out three of the four batters he faced, including Torii Hunter, who had homered earlier in the day.

As it happens, Crow was just getting started.

Through his first 13 appearances and 15.1 innings, he surrendered no runs, gave up only eight hits and struck out 15. After finally giving up a run (two in fact) against Oakland on May 7, Crow made seven more scoreless appearances.

A wicked first half led to his election to the American League All-Star team as a rookie with a 2.08 ERA in 43.1 innings.

As we know, Crow’s season didn’t stay on the same path. After such a hot stretch, he could do nothing but regress, and considering that his walkrate wasn’t great in the first half (4.15 BB/9) and batters hit only .243 when putting the ball in play, that’s just what he did. Unfortunately, in stretches, he looked almost lost.

In the second half, Crow’s ERA was 4.34 over 18.1 innings. He walked more batters (5.3 BB/9 in the second half) and batters hit .393 against him after the All-Star break when putting the ball in play.

So which Crow do we believe in? You’ll hate the answer because it’s both. He’s not as good as his first half and not as bad as his second half. Typically, when looking at stats and predicting regression to the mean, it’s a gradual process. In Crow’s case, it was stark and sudden. He threw a lot of innings per appearance in the first half, so perhaps it was a bit of fatigue contributing to Crow’s poor second half.

That being said, for the full season, he threw 62 innings with a 2.76 ERA while striking out more than a batter an inning. Looking at other numbers, his FIP was calculated as 4.11 with an xFIP of 3.34. While Crow walked 4.5 batters per nine innings, his numbers started to spike when he gave up more home runs than would be expected. Crow surrendered a home run on 17.8% of flyballs allowed. The league tends to average about 10%.

Part of that high HR/FB rate is due to Crow being a ground ball pitcher. Pitching primarily as a starter in Double A, Crow induced a grounder 52% of the time. When he moved down the Wilmington, he increased that rate to 63%. As a big leaguer, 51% of balls in play were hit on the ground.

There’s discussion of Crow being part of the starting rotation next season. He started at Mizzou and was drafted as a starter. His performance suggests he may be more successful as a reliever, though. For one, Crow’s walkrate works out to a walk every other inning. If he can manage his control, his stuff is good enough to be a factor. With a fastball that averaged 95 mph in 2011 and a sharp slider that he’ll throw just about any time (and often with two strikes), he misses a lot of bats. Only Greg Holland and Louis Coleman had a higher swinging strike percentage.

The problem with Crow in the rotation is between the fastball and slider, Crow really doesn’t throw anything else. According to FanGraphs, he threw either of the two 93.3% of the time. He does throw a curveball and has worked on a changeup, but as a reliever he hasn’t resorted to throwing either very often. Perhaps that will be his goal this offseason, as he’ll need at least a third pitch to work out of the rotation regularly.

Crow’s strong overall season will bring him back to Kansas City in 2012 where he’ll be a big part of the pitching staff. He’s got the stuff to be effective as a setup man or the first man out of the bullpen. He could probably close at this level, though he never got a save opportunity in his week-long stint as the team’s “closer” during Joakim Soria‘s 2011 slump.