Is Sonny Gray the Oakland A’s Best Pitcher?

Oakland Athletics rookie pitcher Sonny Gray has had an immediate impact on the A’s rotation since making his first major league start August 10. The 2011 first-round draft pick has a 2.67 ERA across 10 starts and 64 innings. Of his rotation mates, only 40 year-old veteran Bartolo Colon has a lower ERA.

While the A’s starting rotation has the second lowest ERA in the AL behind only the Detroit Tigers, much of this is due to their cavernous home ballpark.

The A’s have amassed a rotation of flyball pitchers with largely unimpressive strikeout rates, and relied on the dimensions of the Coliseum to keep down their HR/FB ratio. xFIP, which estimates ERA from strikeouts, walks, and groundballs, indicates their rotation is in the bottom half of the AL.

Sure Colon might have managed the second lowest ERA in the AL during the regular season, behind Anibal Sanchez, but if you look at his peripherals, it appears he’s running on borrowed time.

Certainly Colon is a strike thrower, but this is due to a heavy reliance on a fastball that averages just 90 mph. His strikeout rate is lower than all but five qualified starters. His success has been based on HR/FB and LOB rates that are way out of proportion with his career numbers. xFIP indicates he is an average pitcher.

Not only does Gray have an excellent ERA, but he has the stuff and the peripherals to back it up. Not only is he the hardest thrower in the A’s rotation, but he also features an excellent 12-6 curveball.

His stuff plays to the tune of a strikeout rate of 24.8%, which is a full four points higher than the next closest pitcher, A.J. Griffin. 

Despite his small frame (listed at 5’11), Gray gets good downward plane on his pitches, and his groundball rate of 53.6% is much higher than anybody else in the rotation. Combine that with a good walk rate, and Gray’s xFIP is on par with aces such as Chris Sale and Clayton Kershaw, albeit in a much smaller number of innings.

The A’s have wisely built a rotation to fit their ballpark, and it has paid off in a big way in 2013. However, rookie pitcher Sonny Gray also has the ability to limit homeruns with strikeouts and groundballs, methods that work regardless of the park dimensions.

Not yet 24, Gray is the best pitcher on the Oakland Athletics.