Rockies building a troubling rotation

Humidor or not, everyone knows that the best strategy in Colorado is to keep the ball on the ground as much as possible. That’s why the Rockies have gotten quite a few questions after an offseason adding Guillermo Moscoso and Jeremy Guthrie. Quite an interesting approach for a team that finished 21 games out last season with an offense based around two players in Troy Tulowitzki and Carlos Gonzalez.

In January, the Rockies added Moscoso after a solid 2011 with the Athletics when he posted an ERA of 3.38 with 74 strikeouts to 38 walks. His FIP was a solid, but unimpressive, 4.22 while his xFIP displayed a troublesome trend at 5.02. In 142.2 major league innings, Moscoso has given up 54.8 percent fly balls and his total of 55.5 percent in 2011 was the most among any pitcher with more than 120 innings. Moscoso is the ultimate fly ball pitcher and is headed to one of the three best home run parks in baseball.

In Oakland, Moscoso was able to mask his fly ball rate playing in the spacious Coliseum, which ranks bottom five in home runs against. His HR/FB rate currently stands at 6 percent, but is sure to increase in Colorado. Even a slight uptick in home runs will damage his value and his addition to the Rockies.

On top of the home runs, Moscoso has benefited from a bit of luck in BABIP. His current rate of .234 is unsustainable for any pitcher even with an elite defense. Once his BABIP and HR/FB regress to the mean, you are potentially looking at a below average to replacement level pitcher. His K/BB of 1.91 is pedestrian and his only skill so far has been to pitch in a spacious home park with a bit of luck on balls hit in play.

Adding Moscoso might have been worth the sho,t as he has been able to post solid seasons in the minors (though he’s had some rough seasons as well). The problem came when the Rockies decided to add Orioles starter Jeremy Guthrie on Monday. He is not as prone to the fly ball as Moscoso, but has a nearly perfect one to one ratio of ground balls to fly balls.

While not able to hide from the home run in Baltimore, Guthrie has been another one of those who has been able to maintain some level of control over his BABIP. His current rate of .273 is slightly below league average and helps him beat his FIP and xFIP. His career ERA of 4.19 beats his FIP of 4.68 by nearly half a run. Baltimore might not be a pitchers’ park, but looking at most home run factors, Coors Field is still a much tougher place to keep the ball in the yard. With a career HR/FB of 10.2 percent it’s tough to see that exploding upward, but we can be fairly certain it won’t go lower.

Guthrie will see some boost from the switch to a weak NL West from his days in the AL East and he’ll enjoy a few road games in San Francisco, Los Angeles and San Diego. Moscoso won’t get much out of the switch except some boost from the weaker lineups of the NL.

The switch from Jason Hammel to Guthrie is probably a neutral to slight upgrade in terms of wins in 2012. The move for Moscoso, on the other hand, could be a big problem for the Rockies. His small sample size of data so far tells us he is absolutely not a pitcher who is likely to succeed in Coors Field. That move could be a big regret for the Rockies front office in 2012.