January 18, 2013

Raising Aces

Then and Now: Giology

by Doug Thorburn

Gio Gonzalez had a breakout season in 2012, finishing third in the Cy Young voting in his first year with the Washington Nationals. Despite the dominant campaign and a track record for success, Gonzalez had to live in the shadow cast by the spotlights surrounding teammate Stephen Strasburg, putting up with the common perception that he wasn’t the best pitcher on his own team, let alone the whole league.

The trade that brought Gonzalez to the nation's capital marked the fourth time that the southpaw had been dealt since being selected by the White Sox in the supplemental round of the 2004 draft. The Pale Hose shipped him to Philadelphia as the PTBNL in a deal that brought Jim Thome to the south side in November of 2005, only to re-acquire Gonzalez a year later (along with Gavin Floyd) in a swap that put Freddy Garcia in purple pinstripes. The Sox then broke up with Gio for a second time after just 13 months, packaging him to Oakland in a deal that brought Nick Swisher to Chicago. 

Gonzalez made his major-league debut during his first season in the A’s organization, and over the next few years he would hone his game under the tutelage of Oakland's coaching staff. The four seasons that Gonzalez spent with the green n' gold represent his longest stretch with an organization in his nine-year professional career, and though his poor walk rates made some doubt his ability to prevent runs away from the favorable home environment in Oakland, the lefty fooled the masses by advancing his game to another level during his 2012 season with Washington. Here's a look at what has changed between his second season and now.

	IP	ERA	BABIP	O-Avg	O-OBP	O-SLG	K %	BB %	HR %	WARP
2009	98.7	5.75	.363	.288	.375	.471	24.0%	12.3%	3.1%	1.1
2012	199.3	2.89	.271	.206	.283	.299	25.2%	9.3%	1.1%	3.4

Gonzalez had a handful of disaster starts in 2009, including an 11-run shellacking against Minnesota that included four homers in less than three innings (incredibly, the A's would come back to win that game 14-13, as part of an epic season of Oakland comebacks). It was his second run through the majors and a strikeout rate of better than a batter per inning inspired optimism, but his recurring problems with free passes and hard-hit baseballs were devastating to Gio's bottom line. 

Gonzalez’ true outcome ratios regressed toward the league mean in 2010 and 2011, but he had much more success on batted balls on his way to an ERA in the low threes. The K rate would climb back above a batter per inning in 2012, and his strikeout percentage of 25.2 percent was second only to Clayton Kershaw’s in the National League. All of his numbers are trending in the right directions, with an ERA that has shrunk along with his walk rates every year since 2009 and with a four-year Wins Above Replacement trend of 1.1, 1.7, 2.3, and last season's 3.4.

Gonzalez was remarkably consistent in the first half of 2012, and after surrendering four earned runs in less than four innings during his first start of the season, Gio went on a 25-inning scoreless streak and would not allow more than three runs in any of his next 13 starts. He was steady if not a workhorse, working six full innings or more in 25 of his 32 starts yet only breaking the seven-inning barrier in three of those games. The Nats have a fragile rotation, with Tommy John survivors Stephen Strasburg and Jordan Zimmermann requiring workload management, but the six-inning starters will be bolstered by a deep Washington bullpen that just added Rafael Soriano to the late-inning mix.

I covered the statistical highlights of Gio's season at the start of the playoffs:

With the end of the season comes debate about awards, and in Washington, the Cy Young talk has been dominated by hometown nominee Gio Gonzalez. Traditionalists may point to the lefty's 21 victories as proof of his worth, but his case is further substantiated by his league-leading rate of 9.4 strikeouts per nine innings and a sub-3.00 ERA, in addition to VORP and WARP totals that place him in the top five in the National League. Gonzalez is virtually tied with Clayton Kershaw for the lowest hit rate in the majors among starting pitchers, allowing just 6.7 hits per nine innings, which has combined with a career-low walk rate to knock 18 points off of his previous-best WHIP, pleasing his fantasy managers as well as Davey Johnson.

Gonzalez has maintained a better-than-average BABIP for the past three seasons, but playing in front of the NL's best defensive unit has propelled him to the Kershaw zone, with a BABIP of .271. Even more impressive is the sub-.300 slugging percentage that Gio has allowed to opposing batters this season, including just nine homers and an opponents' Isolated Power under .100 in his 199 innings of work. His opponents' slugging mark of .299 leads all of baseball by a healthy margin, sitting 19 points better than runner-up David Price (Medlen sneaks in below Gio if we lower the inning threshold). Gonzalez is throwing his signature curve less often this year, but when he unleashes the big breaker, it still has enough action to make ultimate slugger Ryan Braun look bad.

The curveball is Gio's signature pitch, and back in 2009 he had a habit of dropping the big bender in the dirt, keeping his catchers busy with exterminating batters after the swing. The result was a ton of whiffs, but hitters were often rewarded for their patience when they showed the discipline to lay off the curve. Gonzalez had an overwhelming tendency to resort to fastballs when behind in the count, and in 2009 he threw his heater more than 80 percent of the time when the batter had the ball-strike advantage. That predictable pattern combined with Gio's shaky fastball command gave opposing batters a huge advantage, allowing them to sit dead-red on fastballs while Gonzalez played right into their hands.

?Gonzalez has since honed the curve to the extent that he can command the pitch within the strike zone, generating a 30-percent-higher frequency of strike calls with the curveball in 2012 than he had in 2009. His curve is sometimes referred to as a “slurve” due to the curveball velocity and the slider-shaped tilt on the pitch, but his bender's pitch trajectory is determined more by his low-3/4 arm slot than any sort of hybrid supination angle.

Gonzalez breaks the typical pattern of pitchers who lose velocity as they age, as the left-hander has gained one-and-a-half ticks on his average fastball since 2009, cracking 94 mph on his typical heater in 2012. The uptick in velo could be due to a couple of factors, ranging from improved conditioning to a more efficient delivery.

Gio's noteworthy improvement with fastball command indicates that his velocity gains are mechanical in nature, and his use of a two-seam fastball gives Gonzalez another option for keeping hitters from squaring up his pitches. The pitch has enough downward movement to earn a “sinker” classification on his PITCHf/x profile, and it has the arm-side run to keep right-handed batters wary of pitches that could drift away from the bat. Gonzalez also mixes in an effective change-up, which carries greater downward movement than the sinker while bringing a seven-mph drop in velocity to keep hitters off-balance.

Mechanics Report Card

	2009	2012
Balance	60	60
Momentum	55	60
Torque	65	65
Posture	60	70
Release Distance	55	65
Repetition	30	50

For an explanation of the grading system for pitching mechanics, please consult this pair of articles.

Gonzalez had an excellent mechanical profile in his sophomore season, earning above-average marks in every category except the final, most important grade of them all. The southpaw struggled heavily to repeat his delivery in '09, largely due to a closed stride that went against his natural signature. Some players can line up the motion with a closed stride, as their signature dictates a closed angle of the hips to bring the shoulders square with the target, but Gonzalez is not one of these pitchers. His signature calls for a stride that is directed straight at the plate, aligning his spine with the plate in order to achieve his ideal extension at release point.

With the closed stride, Gonzalez would reach full extension while his body was rotationally aligned with the left-hand batter's box, and in order to angle the ball toward the plate Gio had to over-rotate the shoulder axis—imagine that you’re bowling, lined up with one set of pins but rolling the ball into the adjacent alley. The following GIFs highlight the difference exceptionally well, with an experiment that is as controlled as it gets in our non-laboratory environment: the clips are separated by three years in time, yet both GIFs were shot from the same dead-center camera angle at Fenway Park, and in both cases second baseman Dustin Pedroia fell victim to a loopy curve for the swinging strikeout. Observe.

The straight-away camera angle helps to isolate Gio's relative stride direction. In 2009, he clearly strides at an angle toward the left-hand batter's box, exemplifying a very common strategy that is invoked by left-handed pitchers to create a deceptive angle, but which often disrupts a lefty's natural motion, as it did with Gonzalez. Each pitcher has a unique hip angle that allows his delivery to line up with the target, and that angle is impacted by the direction of stride and the resulting position of the feet.

At the National Pitching Association, we had a simple drill that we used to determine a pitcher's signature hip angle in order to square the shoulders to the target in sequence: instructing the athlete to play catch from his knees. The pitcher would start at a 45-degree angle, opened toward the target, and make a couple of throws. The player who opened up the front shoulder and over-rotated while playing catch would then close his hip-angle to align the gears of his delivery, while a pitcher who “threw across his body” by under-rotating the shoulder axis would open his stance wider than 45 degrees. Whatever hip angle produced the best extension would then become the anchor for the pitcher's stride direction.

Gonzalez has made a number of subtle adjustments to his motion over the past three years, and though a switch to a more direct line to the plate is the most obvious change, he has steadily improved his efficiency to earn an exceptional GPA on his mechanics report card. That said, his greatest weakness is still the critical element of timing.

There is not a huge discrepancy in Gonzalez' position at maximum leg lift, but he has instigated a bit of a twist into max lift, deriving similar benefits as the reverse-rotating King Felix. Gonzalez exhibits a smoother transition out of max lift in 2012, with an uptick of momentum that helps to extend his stride.

The disparate stride directions are apparent in the above stills, in which the front foot of the 2009 delivery lands far to the left of the centerline, but the 2012 motion is just a shade off-center, which Gonzalez is able to repeat with greater consistency. In addition to throwing a wrench into timing and sequencing, the closed stride of 2009 also represented an inefficient stride-path, effectively limiting his distance at release point.

In the above release-point pictures, one can see the ripple effect of the closed stride by looking at the pitcher's shoulder axis and visualizing the location toward which his shoulders are aligned. Looking at the 2009 shot, Gonzalez appears to be aiming at the catcher's knee-guard, outside the zone to the left of the plate; in the 2012 release-point picture, his shoulders are aligned with the left-half of the plate. The left-hander also has better posture in the right-side still, with a spine angle that is approaching the 80 ceiling, further contributing to his release-point extension and helping to establish the functional basis for his statistical breakout.

Doug Thorburn is an author of Baseball Prospectus. Follow @doug_thorburn
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