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May 6, 2009

Zumaya's Zooming

Bouncing Around

by Ben Lindbergh

Three years ago, Joel Zumaya took the AL by storm, flashing an overpowering fastball on his way to a full season of stellar relief. Since 2006, though, he's fallen on hard times. Now that the big righty has recently reclaimed his role in Detroit's bullpen, let's take a look at his prospects for future success by using all of the tools at our disposal.

Zumaya broke camp as a member of the Tigers' bullpen in 2006, after fellow rookie Justin Verlander had claimed a rotation spot in spring training. Except for a single appearance in relief as a 17-year-old in the GCL, Zumaya had worked exclusively as a starter in the minors, but his migration to the pen didn't come as a complete surprise. Although Baseball America ranked him among Detroit's top four prospects in each year from 2004-2006, talent evaluators frequently cited his intensity, max-effort delivery, inconsistent mechanics, limited repertoire (before 2005), and three DL stints (for back and shoulder spasms) as factors arguing for a shift to short relief work.

Zumaya's performance in the pen for the pennant winners largely quieted concerns about his departure from the rotation, as he pitched 83 1/3 innings and struck out 97 batters en route to a Rivera-esque 1.94 ERA. Zumaya was a two-win reliever for a team that finished with a two-win cushion in the American League's Wild Card race, and the value of his performance cannot be discounted. Still, even at the height of his success, astute observers could find reason to temper their enthusiasm about his prospects for the future. Zumaya benefited from a .254 BABIP, a below-average HR/FB rate, and a sky-high 87.6 percent rate of runners left on base; effective pitchers tend to post higher strand rates, since they avoid allowing so many baserunners, but even the Sandman himself has matched that figure only once in his career. Zumaya's FIP and tRA were 3.34 and 3.18, respectively—estimable figures, if somewhat less impressive than his otherworldly ERA. However, his xFIP (FIP, adjusted for a normalized HR/FB rate) and tRA* (tRA, with component factors regressed to the league average), which function as better predictors of a pitcher's future ERA, were 4.15 and 3.86. I do not serve up this statistical soup to suggest that we could have entirely foreseen Zumaya's future FIPs as he walked off the field in the ninth inning of the '06 Classic's final game; after all, he was not yet 22 at the time, so expecting some improvements in his peripherals would have been reasonable. But after the good fortune he enjoyed during his debut, we shouldn't be terribly surprised that he's spent the past two seasons holed up in base camp at the foot of the peak he established three years ago.

Zumaya's body has been through a lot since those heady days. He became memorably unavailable during the 2006 playoffs as a result of a repetitive stress injury stemming from overuse of Guitar Hero and excessive autograph signing, and in April of the following year he tore a tendon in his right middle finger. Following the 2007 season, a 50-pound box fell on his shoulder, requiring career-threatening reconstructive surgery. Last August, doctors discovered a stress fracture in the same shoulder that may never heal, and he just recently returned from a DL stint for muscle cramps and shoulder soreness. In order to determine whether injuries have subjected his process to a decline as steep as that of his product, we'll turn to Pitch-f/x.

Any mention of Zumaya begins (and usually ends) with his calling card: a blistering four-seam fastball, which regularly touched triple digits during his debut season. Zumaya wasn't always a flamethrower—in fact, he fell to the 11^th round of the 2002 draft out of high school because his velocity hadn't yet spiked. Baseball America attributed his fastball's subsequent boost in speed to refined mechanics and a 25-pound weight gain; Zumaya credited yoga and a daily long-toss program. Regardless of the true origin story of the pitch, Zumaya arrived in Detroit armed with a valuable weapon, and the fans took notice.