BP: Fixing Javier Vazquez

During Javier Vazquez's first home start this season, Yankees fans wasted little time before booing the struggling starter, who had been rocked in his 2010 debut at Tampa Bay and was off to another shaky start. By the time the boos finished raining down during his most recent outing on May 1, Vazquez, who was acquired from the Braves in an offseason trade, had surrendered three homers, seven hits and five runs in three-plus innings against the light-hitting Chicago White Sox.

Forgive Yankees fans for not greeting Vazquez with open arms, as they've spent years trying to erase their last memory of him in pinstripes. Down 2-0 to Boston in Game 7 of the 2004 American League Championship Series with the bases loaded and one out, Vazquez came on in relief and surrendered a back-breaking grand slam to Johnny Damon.

Despite a stellar 2009 season in Atlanta, Vazquez's return was greeted with apprehension given the his fly-ball tendencies and Yankee Stadium's soaring home run rate during its inaugural season. Alas, Vazquez has been brutal thus far, putting up a 9.78 ERA and yielding eight homers in 23 innings. Half the Yankees' losses thus far have coincided with his turn in the rotation. He will start Tuesday night at Detroit after the Yankees pushed back his turn so that he would not have to pitch at Boston this past Friday. Can Vazquez turn it around? The data aren't all that encouraging. Allow me to explain.

Last year, Baseball Prospectus colleague Eric Seidman examined the enigma that is Vazquez and showed that he performed significantly below average with runners on base. The average pitcher's opposing-batter performance with men on base rose by 14 percentage points of on-base percentage and seven percentage points of slugging over his showing with the bases empty; Vazquez's numbers rose by 38 percentage points of OBP and 42 percentage points of slugging. If you break down Vazquez's performance by league going back to 2000, the difference is even more dramatic:

Vazquez: Bases empty vs. men on base

Javier Vazquez has been horrendous in the AL with men on base.

What's going on? It's not simply a matter of serving up taters while surrounded by AL baserunners; Vazquez's rate of home runs per plate appearance edges up only a hair in both cases. His other peripherals are moving in the wrong direction to an even greater extent:

Not about the home runs

Although Vazquez's home run rate is similar with or without men on base, all his other numbers jump.

Vazquez's strikeout rate with men on base during his AL tenure falls off more drastically than it did during his NL tenure. Furthermore, worse results on the increased number of balls put into play are exacerbating the problem. During the time in question in the NL, his BABIP splits have been unremarkable: .302 (the same as his overall career mark) with the bases empty and .306 with men on. In the AL, his BABIP vaults from .282 when empty to .326 when occupied. And even beyond his struggles while pitching from the stretch, there are other reasons to be concerned.

Comparing Vazquez's 2010 Pitch f/x data with that of previous years, the most obvious difference is that his average fastball velocity is about 2 mph slower than last year, falling from 91.1 to 88.9. He had been somewhere between 91 and 92 in every year since 2005. That's a significant drop; not many right-handers can succeed with fastballs below 90 mph. Vazquez is throwing fastballs -- both four-seamers and two-seamers -- a bit less frequently than in 2009 and generating fewer whiffs (swings and misses):

Fastball: Finding bats

The 2010 Vazquez is generating fewer missed bats with his fastball than he was last season.

Perhaps of more significance, the whiff percentage on his off-speed stuff -- curve, slider and changeup -- has fallen even more dramatically:

Off-speed pitches: Finding more bats

The 2010 Vazquez has been worse with his off-speed stuff than his fastball.

Before Vazquez's last start, TV analyst and former big league pitcher Al Leiter suggested that Vazquez's current troubles were rooted in his delivery. "He's getting under the baseball" rather than on top of it, causing his pitches to flatten out, Leiter said. FanHouse's Frankie Piliere, a former big league scout, similarly blamed nagging mechanical difficulties, noting that Vazquez isn't driving over the top of his front leg and getting his arm fully over the top, instead rotating around his torso and shoulder and coming from a lower arm angle. In the process, he is robbing himself of velocity and compromising his command.

Even with Vazquez's patchy situational stats, it's simply too early to resort to panic over a pitcher not expected to carry the team and whose overall track record is as long and as solid as his. Expect Brian Cashman, Joe Girardi & Co. to resist the temptation to resort to more drastic measures -- firing squad, stoning or Clockwork Orange-style loops of the 2004 ALCS -- while riding out the storm for a while longer. Despite Vazquez's struggling, the Yankees would be in the postseason if the season ended today. Giving Vazquez a chance to work through his problems is a luxury they can afford.

Jay Jaffe is an author of Baseball Prospectus.