FanGraphs: The problem with Peavy

The White Sox acquired Jake Peavy from the Padres at last year's trade deadline to be their ace for 2010 and onwards. In 2010 so far, Peavy has performed nowhere near the part, and that continued Wednesday night when he allowed six runs in 6 2/3 innings during a 6-5 loss to the Rangers. But a close look at Peavy's performance shows that's it pretty obvious why he's is struggling.

Simply put, the 28-year-old right-hander is not finding the strike zone. So far, Peavy has hit the zone on just 46.1 percent of his pitches, a mark which places him in the bottom third of the league among starting pitchers. There are some successful pitchers down there with him, including teammate Mark Buehrle and Royals ace Zack Greinke. However, when Peavy has missed the strike zone, hitters simply haven't chased. Buehrle has induced swings on over one-third of his pitches out of the zone, and Greinke on more than 27 percent. Peavy has managed to induce out-of-zone swings only 24 percent of the time.

Naturally, this has led to a career high 38.2 percent of his pitches to be balls and a career high 6.28 walks per nine innings. Peavy's strikeout rate has also plummeted to a career low 6.91 per nine, after being above a strikeout per inning every year but one since 2004. This combination of missing the strike zone and an inability to avoid contact has allowed players to sit back on a misplaced pitch in the heart of the strike zone and to simply take a walk if that pitch doesn't come.

One possible explanation is an increased use of his changeup, which he had an extraordinarily difficult time controlling in Wednesday night's start against Texas. He's thrown it 12.6 percent of the time this year after not topping 9.4 percent with that offering since 2005. He threw the pitch 11 times against the Rangers and only managed to get three called strikes and one swinging strike. Meanwhile, all of his other pitches were strikes at least 58 percent of the time. He had similar struggles with the pitch the outing before against Tampa Bay, only throwing 40 percent of his 20 changeups for strikes. His curveball use is down to account for this rise in changeups, and the curveball has been a pitch he's been able to get strikes with this season, drawing 71 percent and 61 percent strikes respectively in his last two starts.

Regardless of the reason, Peavy needs to start finding the strike zone, and fast. The White Sox have already fallen five-and-a-half games behind the Twins, and if they don't have the ace that they traded four prospects for last season, their playoff door will close in a hurry.

Jack Moore is a writer for FanGraphs.