Ulnar Collateral Ligament Reconstruction and Its Effect on Yearly and Career WAR

Tommy John’s Legacy

Tommy John belongs in the Hall of Fame. With 12 more wins to his name, he almost certainly would be. However, his record 188 career no-decisions held him back. With more advanced analytics, his case becomes clear. In terms of all-time WAR, Tommy John sits in 22nd among pitchers, sandwiched between John Smoltz and Phil Niekro. His impressive total can be attributed largely to his astounding longevity, pitching 26 seasons in MLB. This becomes even more incredible when his ulnar collateral ligament (UCL) is taken into account. Tommy John underwent the first UCL reconstruction (UCLR) ever performed on a pitcher in 1974. After taking the 1975 season off, he went on to pitch 14 (!) more seasons, essentially putting in an entire career’s worth of work after a still experimental surgery.

Tommy John surgery, as it is now called, is still extraordinarily common in Major League pitchers, and the specter of a UCL tear haunts pitchers and general managers alike. But how does actually undergoing Tommy John surgery affect a player’s ability to perform? There have been considerations that Tommy John surgery actually improves performance, though this assertion is controversial at best.

Brief Review of Current Literature

A 2014 cohort study from Erickson et al. investigated MLB pitchers who underwent UCL reconstruction and compared performance measures between those who underwent surgery and controls that were matched by age, BMI, position, handedness, and MLB experience. Also measured was the rate of the return to pitching after surgery. This study showed that 83% of those who underwent surgery were able to return to pitching. In terms of performance, it was found that performance significantly declined the year before surgery and improved after surgery in the experimental cohort (as measured by losses, losing percentage, ERA, walks, hits allowed, runs, and home runs allowed). The surgical group even improved in some measures after surgery as compared to the controls, specifically in terms of losses, losing percentage, ERA, walks allowed, and hits allowed per inning.¹

Another cohort study shortly followed in 2014 from Drs. Jiang and Leland that investigated the velocity of MLB pitchers after UCL reconstruction. In this study, of those who were able to return to pitching at the major league level, the mean velocity they were able to reach was unchanged with respect to the control group. In addition, performance measures of those who received surgery were not affected relative to the control group (in this case ERA, BAA, W/9, K/9, and WHIP).²

Yet another cohort study came in 2015 by Marshall et al., which compared 33 MLB pitchers who received Tommy John surgery to 33 age-matched controls. These groups showed mixed results in terms of performance, with little effect of surgery on ERA and WHIP. Surgery was correlated instead with a decline in innings pitched and BB/9. Of note, those who received surgery had significantly shorter careers after surgery than the control group (a difference of 0.8 years (P<0.1)).³

In 2019, Marshall et al. released a study of 46 MLB pitchers who received UCLR. Again the return to MLB was 82%, consistent with previous literature. In this study, however, the type of tear (complete versus partial, chronic versus acute, proximal versus distal), graft type (gracillis versus palmaris), and technique were evaluated for their effect on ultimate performance. Interestingly, the palmaris graft was superior in returning players to MLB as well as allowing a longer career (although this cohort of patients was significantly younger than the gracillis cohort). Distal tears were associated with higher velocity than proximal tears as well as increased pre-surgical treatment. However, proximal tears that were repaired resulted in improved post-surgical performance and velocity that matched the performance and velocity of the distal tear cohort. Pitchers with reconstructed complete tears were able to play longer after surgery than pitchers with repaired partial tears. Complete tear pitchers also had a better ERA before injury and had a better WHIP and K/9 after surgery compared to partial tears. Those with chronic tears enjoyed a significant improvement in postoperative ERA compared to their preoperative numbers. This study suggests that the effect of a UCL tear and reconstruction on performance and longevity may be heavily dependent on the individual type of pitcher, type of injury, and type of reconstruction rather than being a predictable homogeneous career event.⁴

My Brief Pseudoscientific Contribution

Previous literature has compared relatively small cohorts and investigated individual performance metrics. This brief report investigates the more global effect UCL tears have had. Specifically, I aimed to measure the effect UCL tears have had on the overall WAR over the course of the careers as well as the average yearly WAR of those who have suffered UCL tears compared to pitchers overall in the same era. The goal of this study was to determine if a UCL tear led to a decrease in the average yearly WAR and the career WAR of those involved and, if so, to determine if this was due to performance changes or career shortening.

Methods:

I went through the list of every MLB pitcher who underwent UCL reconstruction according to MLBreports.com. I exported data for each year of their career from FanGraphs.com after adding WAR to the dashboard (n=260). I excluded anyone who was still active (or potentially still active), and anyone who had never pitched in an official MLB game. These 260 players comprised the Tommy John (TJ) group. I compared the average yearly total WAR of these players to a random cohort (selected using a random number generation function in excel) of 101 pitchers from the same era (1963-2017). I also compared career WAR and average career length. Overall career WAR of the TJ cohort was also compared to the overall WAR totals of every pitcher from that era according to FanGraphs (n=3106). T-test for means was used to determine significance and confidence intervals.

Results:

The average yearly WAR between the TJ group and the overall sample follows relatively the same trajectory, however there is a conspicuous peak in the TJ group at years 15-18 (Table 1). There is a higher proportion in the TJ group that only played in MLB for 1-3 years with a notably larger chunk of the overall group that lasted between 7 and 11 years (Table 2). There was no significant difference detected between the TJ group and the overall sample in average career WAR or overall career WAR. However, the TJ group did pitch for fewer seasons than the overall sample group (-1.84 years, 95% CI [-2.78 – -0.89]) (Table 3). Also, when the TJ group was compared to all 1823 pitchers of the era between 1963 and 2017, the TJ group did have a significantly lower average career WAR (-3.43 95% CI [-5.26 – -1.61]) (Table 4).

Raw data and graphs are available in this Workbook.

Discussion and Conclusions

According to this data, UCL tears and reconstruction have not had an obvious effect on the yearly WAR expectation of the players involved. Though less specific than previous studies on the topic, it is likely that UCLR players end up with little difference in their performance level if they are able to successfully return to play. If there were a predictable decline in performance after UCLR, the yearly WAR totals should be expected to decrease in those who underwent the surgery even though this study does not differentiate between pre-surgical and post-surgical numbers. The surge in yearly WAR of the TJ group after year 15 is likely due to the small sample size during these years, as not many players last this long in MLB (Tables 1 and 2). A couple outliers, including Tommy John himself, artificially inflated the yearly WAR totals of the TJ group during these years and it is unlikely to represent a late career benefit of having UCLR.

The data presented here supports previous data that the career of someone who undergoes TJ is shortened. In addition to previous research, the cohort used in this group combines both those players who were able to return to MLB and those who were not. Many players who only lasted 1-3 years in the TJ cohort were likely of the 20% of players who received the surgery and were unable to return to MLB play.

Of note, the average overall career WAR of the TJ group was significantly different than the average career WAR of every pitcher in the post Tommy John era. This is most likely explained by the years lost due to Tommy John surgery, either in the year or two spent in rehab or the inability to return entirely. The similarity of the average yearly WAR of the TJ group and the sample overall group does not support a claim that the difference in average career WAR is due to performance decrease. The consistency in the literature of the decrease in pitching years that is reproduced in this brief report supports the notion that the decrease in average career WAR is due to less time spent pitching and not performance inhibition.

This study looks at the overall impact of TJ surgery on a career. It does not look at before and after effects of TJ surgery. Therefore it’s possible that a dip in performance occurred due to TJ surgery without being detected. However, even in this data, that is unlikely, as the TJ cohort had significantly shorter careers, and still did not show a decrease in career WAR compared to the smaller sample group. Even in the larger overall cohort, which showed a difference in career war, the difference can likely be attributed to the career length difference. If there exists a performance dip due to TJ surgery, it is either so small that it is difficult to measure, or those prone to needing TJ surgery were actually the highest performers before their surgery, making up for their post-surgery dip in performance. Both cases seem unlikely but are worthy of further investigation.

References

1. Erickson, B.J., et al., Rate of return to pitching and performance after Tommy John surgery in Major League Baseball pitchers. Am J Sports Med, 2014. 42(3): p. 536-43.
2. Jiang, J.J. and J.M. Leland, Analysis of pitching velocity in major league baseball players before and after ulnar collateral ligament reconstruction. Am J Sports Med, 2014. 42(4): p. 880-5.
3. Marshall, N.E., et al., Pitching performance and longevity after revision ulnar collateral ligament reconstruction in Major League Baseball pitchers. Am J Sports Med, 2015. 43(5): p. 1051-6.
4. Marshall, N.E., et al., Major League Baseball Pitching Performance After Tommy John Surgery and the Effect of Tear Characteristics, Technique, and Graft Type. Am J Sports Med, 2019. 47(3): p. 713-720.