Pitchers Recovering From Arm Injuries

Introduction

With arm injuries becoming more and more prevalent in Major League Baseball, teams frequently have to figure out what kind of performance to expect from a pitcher coming back from a serious injury. In this study I set out to see how pitchers perform in their first two years after surgery compared to their pre-surgery form.

Overview

I looked at a sample of 39 starting pitchers, encompassing 42 seasons, over the past 10 years that missed a significant amount of time due to an elbow or shoulder injury. I then compared their performance in the last healthy season to their first healthy season back and the season immediately after it. To be considered a “healthy season” for this study a pitcher had to throw at least 80 innings. I did this to get a more accurate indication of the pitchers performance in their last season and first season back, and to not include small samples if a pitcher got hurt in April or came back in September. If a pitcher had no “healthy season” back then I used the season with the most MLB innings out of the two seasons after injury. I excluded all pitchers that never returned to the majors from the study.

To judge pitchers performance I looked at five things: ERA, FIP, strikeout percentage, unintentional walk percentage, and average FB velocity. I chose these measurements because I believe they show the pitchers overall effectiveness (ERA, FIP), stuff (K%), command (UBB%), and arm strength (FB velocity).

I also broke down the data by elbow and shoulder injuries. It is an accepted belief in baseball that shoulder injuries are worse than elbow injuries and harder to come back from. I wanted to see how much harder it was to come back from, and if the statistical decline for pitchers with shoulder injuries was greater than those with elbow injuries.

All Pitchers

ERA FIP K% UBB% Avg. FB Velocity Total Last Healthy Season 3.78 4.08 18.75% 7.63% 91.08 Total First Season Back 4.23 4.17 18.58% 7.29% 90.19 Total Second Season Back 3.72 3.78 18.96% 6.80% 90.33

As you can see in the chart above, the ERA and FIP of pitchers in their first year back are higher. Strikeout rates also showed a substantial decline, while walk rates actually improved. The average fastball velocity for these pitchers also decreased as you would expect. The fact that strikeout rates went down by .17% might not seem like a lot, but when you take into account that strikeout rates have been going up steadily over the past ten years, it is actually a larger gap in performance.

MLB Average Strikeout Percentage

2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 16.5% 16.8% 17.1% 17.5% 18.0% 18.5% 18.6% 19.8% 19.90% 20.40%

Naturally, the first full healthy season back is generally 2-3 years after the injury. If they were keeping up with the league average their strikeout percentage should actually go up about about a percentage point, so what looks like a small decrease is in fact quite significant. As for walk rates, there are two competing factors in play. Often times increased wildness is a sign of a larger problem; therefore an elevated walk rate in the season a pitcher blew out could have been an indication of a looming issue. Consequently, walk rates in the last season before surgery may be higher than a pitchers normal level, and by getting their arm fixed, it would gravitate back to their typical performance. The competing philosophy is that control is the last thing to return after elbow or shoulder surgery. Looking pitcher by pitcher it was a 50/50 split with 20 having their walk percentage increase, 20 decrease, and 2 remaining essentially the same in their first year back.

Pitchers in their second year back improved greatly, showing improvements across the board. The sample in year two went down to 26 of the 42 pitcher seasons we started out with. Some dropped out due to age (John Smoltz), re-injury (Johan Santana), or 2014 being their first year back (Michael Pineda). One reason why the numbers in the second post-surgery year improve so much is that to make it to year two you probably had some modicum of success in year one. The pitchers that failed to come back to their pre-surgery form (Mark Mulder, Jason Schmidt, etc.) had their poor stats affect the first year after surgery numbers but are washed out of the second year numbers. Even taking this into account, there are definitely some substantial improvements in year two. Eighteen of the 28 pitchers lowered their ERA in their second season after surgery.

Elbow Injuries

Elbow injuries are generally considered less serious than shoulder injuries. The success rate of coming back from Tommy John surgery is pretty high now, with some people even going as far as to say that pitchers come back stronger after getting it done. The numbers do in some way back that notion as pitchers in their second year post-surgery posted better numbers then they did before getting hurt.

ERA FIP K% UBB% Avg. FB Velocity Last Healthy Season Elbow 3.75 3.99 19.42% 7.98% 91.49 First Season Back Elbow 4.06 4.03 19.22% 7.49% 91.04 Second Season Back Elbow 3.60 3.61 19.77% 6.79% 91.38

As you can see in the table above, pitchers do struggle a bit in their first season back, but in year two not only do they improve based on the previous year, they also improved their pre-surgery statistics in all aspects except a small decrease in average FB velocity. Looking specifically at the 18 pitchers that had two seasons after elbow surgery, 11 of the 18 improved their ERA the second season after surgery. Although the data was split regarding average velocity and K%, with about half the pitchers having better numbers the first year after surgery and half the second season, many showed a substantial improvement in their walk rate in season two. This is interesting since it does support the belief that control is the last thing to come back post-surgery.

Shoulder Injuries

Shoulder injuries are believed to be much more damaging to a pitcher’s future than elbow injuries. Part of the reason for this is that Tommy John is so prevalent now, and you see so many people come back from it, it is considered in some ways a routine surgery. Shoulder injuries on the other hand are less frequent and in recent memory we have seen it more or less end the careers of big time pitchers like Mark Prior and Brandon Webb. The numbers in this small study do show that pitchers with shoulder injuries are less likely to get back to a full season of pitching than those with elbow injuries. Eighteen of the 21 (86%) pitchers I looked at with elbow injuries returned to a full season work load (with Brett Anderson still a possibility to get there), while only 11 of 19 (58%) of those with shoulder injuries (Michael Pineda could still do it moving forward) rebounded to even make it over the 80 inning bar one more time in their career.

A couple of pitchers (Johan Santana and Chris Young) who did make it back had another significant shoulder injury during their comeback seasons, although Young made another return to the majors in 2014 after another missed season rehabbing. These numbers also don’t include pitchers like Prior, Webb, Matt Clement, etc. who were established big leaguers at the time of their shoulder injury never to return to Major League Baseball again.

ERA FIP K% UBB% Avg. FB Velocity Last Healthy Season Shoulder 3.79 4.13 18.18% 7.30% 90.36 First Season Back Shoulder 4.49 4.35 17.79% 6.95% 89.08 Second Season Back Shoulder 3.94 4.09 17.48% 6.81% 88.93

The numbers do back up the assertion that shoulder injuries are tougher to recover from than elbow injuries. Pitchers who had shoulder injuries had a steeper drop off their first year after surgery, and failed to rebound to the degree that pitchers with elbow injuries did. If you are a team with a young ace who had shoulder surgery, the beacon of hope is Anibal Sanchez. Sanchez went down with a labrum injury during his rookie season in 2006, and although it took him a few years to recover, over the past five seasons he has been pretty durable consistently supporting a mid 3 ERA, including the 2013 season where won the American League ERA title.

Conclusion

Overall this research backed up most of the common thoughts around the game. Pitchers with elbow injuries generally recovered quicker and more effectively than those with shoulder injuries. The biggest improvement from year one to year two after surgery appears to be with walk rates, as a pitcher’s control is often the last thing to come back after being off the mound for so long.

Although Tommy John surgery does have a high success rate, there are pitchers that never really regained their pre-surgery form. Conversely, shoulder surgeries do have a greater negative impact on pitcher performance, but for every Mark Prior and Brandon Webb there is an Anibal Sanchez or Chris Carpenter that returned and went on to have very productive careers. Obviously there are no certainties in medicine, so franchises shouldn’t expect a guaranteed return for pitchers coming off elbow surgery, or automatically disregard pitchers who underwent shoulder surgery.

In fact, there might even be an opportunity for clubs to take a chance on a free agent pitcher a couple of season removed from shoulder surgery with a low-risk high upside deal. The demand for these pitchers is usually low with all of the uncertainly involved with shoulder injuries. If the deal doesn’t work out there isn’t much invested, but if it does, a team might be able to get a guy like Freddy Garcia who won 12 games in 2010 and 2011 while only making $1 million and $1.5 million those two years since he was coming off of labrum surgery. Pitchers coming off shoulder injuries probably aren’t guys you want to pencil in and count on for 200 innings, but for the money involved they could be low cost lottery tickets that could pay off big for a team.