Guillermo Moscoso: Ticking Time Bomb

Colorado added two more names to its cornucopia of starting pitching options on Monday, trading outfielder Seth Smith to the Oakland A's for lefty Josh Outman and right-hander Guillermo Moscoso. At first blush, getting an arm like Moscoso might seem like a coup for the Rockies. After all, the 28-year-old notched a nifty 3.38 ERA in 128 innings pitched as a rookie in 2011, easily besting the 4.21 average for American League starters. Maybe the former Tiger and Ranger was just a late bloomer, and now he's poised to be a cheap, quality rotation option for the foreseeable future.

Or not. Pitchers can do three main things to succeed over the long haul: miss lumber, limit walks and induce ground balls. Moscoso was decent when it came to issuing free passes, but he was abysmal at the other two. Check out where he ranked among starter pitchers in these three key categories that do a better job of predicting future ERA than past ERA:

Player	K%	BB%	GB%
Moscoso	13.9	7.2	26.7
Percentile Rank	29	54	1

Moscoso's walk rate was better than slightly half of starters last year, and that's actually, by far, his most impressive skill. His strikeout rate was worse than 71 percent of starters, and Baltimore's Brian Matusz (he of the highest ERA ever for a pitcher making at least ten starts) was the only guy to get grounders less often. When it comes to the metrics that extract luck and defense from the equation, Moscoso was a marginal major leaguer.

As you might expect from such an extreme fly ball pitcher, Moscoso pitched up in the zone with his 90-ish mph fastball, low-80s changeup and high-70s slider. Take a look at his pitch location in 2011, and then the league average for right-handers:

Moscoso's pitch location, 2011Average pitch location for right-handers, 2011Thirty-four percent of Moscoso's offerings were located in the upper third of the zone, well above the roughly 28 percent league average. Moscoso didn't get killed climbing the ladder last year in Oakland, surrendering about a homer per nine innings pitched. But that came with a very low home run per fly ball rate (six percent; the league average was close to 10%) while pitching in the Coliseum, which decreases homers hit by lefty hitters by 11 percent and 20 percent for righties. By contrast, Moscoso's new home and fly balls go together like peanut butter and tooth paste: Coors boosts long balls by 13 percent for left-handers and 17 percent for right-handers.

Moscoso's good fortune on fly balls hit, favorable ball park and the lowest batting average on balls in play (.222) among starters save for Jeremy Hellickson helped him post a shiny-looking ERA, but his more skill-based stats paint the picture of a pitcher with an ERA around five. He's basically a right-handed Greg Smith (another former Athletic shipped to Colorado after a superficially impressive rookie campaign) with better control. Don't be surprised if Moscoso, like Smith, turns out to be a Triple-A lifer instead of a solid big league starter.