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August 8, 2014

Raising Aces

The Road to Recovery

by Doug Thorburn

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Much of the focus of the 2014 season has been on pitchers and their busted UCLs, as the ever-growing list of arms that have gone under the knife is scary both for its volume and the level of high-profile names that the list contains. The relative success of Tommy John surgery has somewhat shrouded the reality of the procedure, simultaneously trivializing the difficult decision for a pitcher to cut into his moneymaker while raising the performance expectations when a player returns.

Some pitchers don't come all the back to previous levels of performance, and in extreme cases a comeback can be derailed when the new ligament is compromised during the rehab process, with players such as Cory Luebke and Daniel Hudson requiring a second surgery before getting back on a major-league mound. It is critical to temper expectations for pitchers who are on the road to recovery from UCL replacement, and to appreciate that the comeback trail can be long, with twists and turns along the way.

High-ceiling hurlers such as Matt Harvey and Dylan Bundy are returning to the rubber, but there are a plethora of outcomes that should be considered before we jump back on the bandwagon. Let's examine the cases of three elite pitchers who have walked that rocky road to reclaim their MLB dominance.

Jordan Zimmermann
Surgery date: August 19, 2009

Zimmermann's rookie campaign for the Washington Nationals was cut short when he was stricken by the Tommy John virus. His timetable of recovery was on the shorter side of the 12- to 18-month gap that TJS pitchers typically endure (assuming a clean rehab process), and he was spinning spheres at the highest level just 53 weeks after his run-in with the surgeon's scalpel.

Year IP ERA K % BB % HR % FB Velocity
2009 91 1/3 4.63 23.5% 7.4% 2.6% 94.0
2010 31 4.94 20.0% 7.4% 5.9% 93.0
2011 161 1/3 3.18 18.7% 4.7% 1.8% 94.0
2012 195 2/3 2.94 19.0% 5.3% 2.2% 94.7
2013 213 1/3 3.25 18.6% 4.6% 2.2% 94.8
2014 132 3.00 22.5% 3.9% 1.7% 94.9

Zimmermann was tabbed by Kevin Goldstein as the top prospect in the Washington system prior to the 2009 season, yet his four-star status and no. 56 ranking on that year's Top 101 kept some of the enthusiasm in check. He was tagged a bit in his first go-round of the league, but a strikeout-to-walk ratio better than three teased the right-hander's potential before disaster struck.

2009 - Pre-surgery


The skills were intact when he returned to a big-league mound a year later, but his steep incline of improved performance since the injury is remarkable for any pitcher, regardless of scarring. It is often said that command is the last thing to return for pitchers with elbow woes, but Zimmermann transformed into one of the league's better control artists almost instantly. With a vocal intent to induce weak contact and optimize pitch-count efficiency, the right-hander trimmed his walk rate along with his strikeouts to the pleasure of his ERA, and he has since cemented himself in the 3.00 to 3.25 ERA range for four straight seasons.

2011 - Post-surgery


His ability to pepper the lower shelf of the strike zone is reflected in the low homer rate, and Zimmermann has taken yet another step forward in 2014 by setting new bests in terms of surrendering both home runs and walks, while bringing his strikeouts back up to pre-surgery levels. His pitch speed might be the most impressive development of all, as Zimmermann quickly regained his rookie velocity and has since defied the typical speed-related decline that accompanies pitchers as they age, gradually increasing his average in every year since his return from surgery. He has also improved his mechanics along the way, and the efficiency of his delivery is so strong that he currently earns the highest possible score on the Mechanics Report Card, with an A-grade motion that exemplifies a rare blend of stability and power.

2014


That isn't to say that his delivery is perfect, though he does excel with plus marks in each of the six categories on the report card. The only strike against him is a pronounced tendency toward elbow drag, which occurs due to a combination of heavily-delayed trunk rotation and scapular loading that has a variable effect on the strain placed on his elbow. On the one hand, the delayed rotation allows him to utilize his lower half and core strength to transfer kinetic energy. On the other, the strategy combines with his scapular load to put his arm in a compromising position once he triggers that rotation. In this sense, delayed trunk rotation can be a double-edged sword for a pitcher, simultaneously increasing arm speed and increasing strain on the joint. He has had the elbow drag his entire career, and the connection between elbow drag and elbow injury is well established, meaning that Zimmermann is not yet out of Tommy John's woods.

Stephen Strasburg
Surgery date: September 3, 2010

Everyone knows the story of Stephen Strasburg, who went from ultimate phenom to cautionary tale in the blink of an eye. One moment he was hitting triple digits and making big-league hitters look silly, and the next he was wincing in pain as the Washington faithful watched in horror.

Year IP ERA K % BB % HR % FB Velocity
2010 68 2.91 33.6% 6.2% 1.8% 98.9
2011 24 1.50 27.3% 2.3% 0.0% 97.9
2012 159 1/3 3.16 30.2% 7.4% 2.3% 96.8
2013 183 3.00 26.1% 7.7% 2.2% 96.8
2014 151 1/3 3.39 28.2% 5.3% 2.2% 95.6

2010 - Pre-surgery


Strasburg had a nearly identical timetable for return as his teammate Zimmerman, requiring almost 12 months on the nose between his date of surgery and his re-appearance on a major-league mound. The Nats were cautious with both pitchers in the first full year back in the bigs, but the tight reins on Strasburg received much greater scrutiny given the postseason implications for a Nationals squad that had never played meaningful October baseball. Strasburg exemplified the conventional wisdom of looser control in his first year back and his velocity was a couple of ticks off from the heat that was on display during his rookie campaign. Such discrepancies are easy to excuse in his first year of work post-surgery, but the walk rate and the velocity sat in the same range in the following season, as well.

2012 - Post-surgery


Strasburg has brought down the rate of free passes in 2014 with a career-best walk rate, but the average velocity has continued to tumble. The curve is so devastating that he can register punchouts without his top velocity, and the vicious break on the pitch coaxes opposing batters into chasing even when the right-hander misses his targets badly. In this sense, the walk rate represents a misconception of his pitch command, and the sick movement on his high-speed changeup has also helped to cover for missed targets as he has upped the frequency of the pitch this season. Strasburg has some of the best stuff in the game, and the effectiveness of his secondaries has helped to mask a delivery that has slowly deteriorated.

2014


Many pitchers improve their mechanical stability as they age, building functional strength to improve balance, posture and consistency. But Strasburg has gone in the other direction, and though one would expect that he would take some time to regain his form post-surgery, his stability indicators have gradually worsened over the past three seasons. He has added a bit of extra drop to his center of gravity after max leg lift, and his posture at release point has been much less consistent, sometimes causing him to fall off violently to the glove-side. In his rookie season, Strasburg had a very efficient path of kinetic energy, finishing with his momentum flowing toward the target, but these days it is more common to see him drift off line during his release point and follow-through. He has still has the occasional start where he looks like vintage Strasburg, but that image has been more fleeting in 2014.

2010 2012 2014

Adam Wainwright
Surgery date: February 28, 2011

Back in 2010, Wainwright had established himself as a workhorse in the St. Louis rotation and one of the top pitchers in the game. He experienced a forearm strain at the end of the 2010 season, and the issue carried over the winter and re-emerged in more serious form the following spring, resulting in a ligament tear that was discovered shortly after pitchers and catchers reported for Spring Training.

Year IP ERA K % BB % HR % Sinker Velocity
2010 230 1/3 2.42 23.4% 6.2% 1.7% 91.8
2011
2012 198 2/3 3.94 22.1% 6.3% 1.8% 90.8
2013 241 2/3 2.94 22.9% 3.7% 1.6% 91.7
2014 155 2.26 20.8% 6.1% 0.8% 91.2

2010 - Pre-surgery


The early incidence of injury gave Wainwright a couple of extra months to round into form before he was needed to pitch in a game that mattered, and he was back on the mound at the beginning of the 2012 season. His near–200 inning workload would be a full slate for most pitchers, but for Wainwright it represented a 14 percent drop from his innings count of each of the previous two seasons. He still made his customary 30-plus starts, but the reduction in per-game workload was likely tied to his ailments as well as diminished performance. In that sense, Wainwright exemplified a more conventional performance trend for a pitcher coming off a major injury, with a 1 mph velocity drop in conjunction with a jump in his ERA. The component stats were actually right in line with the two seasons that preceded the injury, and the ERA was inflated by an elevated hit rate that hovered closer to league average.

2012 - Post-surgery


His numbers improved across the board in 2013, culminating in a second-place finish in the National League Cy Young voting with stats that were eerily similar to the two Cy-contending seasons he posted in 2009 and '10. The 3.7 percent walk rate was the best of his career, indicating both the conventional wisdom that control is the last thing to return and the reality that the veteran had improved his game. The velocity also jumped back to pre-surgery levels, adding further fuel to the fires of convention. His run-prevention is even better in 2014, though his velocity has given back a half-tick and the walk rate is back to normal, as his stinginess with respect to the long ball has been the best in baseball this season.

2014


Wainwright has always had a bit of tilt to his delivery along with a heavy dose of flexion, but if one looks closely, his consistency and stability have followed his pattern of run prevention. His release point was a bit more volatile in his first year back from TJS, but his ability to stabilize the delivery and repeat his release point have been better in 2014 than any other time of his career.

***

Every pitcher has a different path to follow in order to conquer Tommy John surgery and rediscover previously established levels of performance. The trio that were put under today's microscope represent the positive tail of the spectrum of possible outcomes, yet each journey tells a different story. They share the commonality of a quick and efficient return to a big-league mound, but the prognosis differs once we dig into the details. Wainwright exemplifies what might be considered a more typical route of performance, with some hiccups in his first year back followed by a return to form in year two; Zimmermann didn't skip a beat upon his return, exceeding all expectations and continuing to raise his theoretical ceiling; Strasburg lost a touch of effectiveness in his first year back, and he has continued down a slow slope of diminishing velocity and mechanical efficiency the further he gets from the surgery. These represent the most positive of outcomes for an elite pitcher, yet their disparate stories exemplify the player-specific nature of rehabilitation and recovery from injury. Their cases help to shine a light on the future of other right-tail pitchers who have succumbed to Tommy John surgery, but by no means offer a template for the career paths of recovering players such as Matt Harvey, Jose Fernandez, and Lucas Giolito.

Doug Thorburn is an author of Baseball Prospectus. 
Click here to see Doug's other articles. You can contact Doug by clicking here

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