1 Introduction

The introduction of ulnar collateral ligament reconstruction (UCLR), or Tommy John surgery, has revolutionized the management of UCL injury and allowed hundreds of professional baseball players to return to resume productive careers.^6,14 A recent study found that up to 25 % of Major League Baseball (MLB) pitchers have undergone UCLR with 89 % returning to play and 78 % achieving the same level of performance prior to surgery.^4,18 Many athletes and coaches may perceive surgery to enhance performance, even in healthy athletes, warranting an investigation of the reliability of reporting of outcomes throughout the literature.¹

A systematic review of 14 studies and 1520 MLB pitchers undergoing UCLR showed that 79 %–87 % of MLB pitchers returned to preinjury levels of pitching as measured by in-game statistics. The results differed across studies with varying metrics reported, including earned run average (ERA), walks plus hits per inning pitched (WHIP), and average fastball velocity after UCL reconstruction.⁵ Makhni et al. examined 147 MLB pitchers who underwent UCL reconstruction and found that performance declined across several metrics, such as percentage of pitches thrown in the strike zone, innings pitched, percentage fastballs thrown, and average fastball velocity (p < 0.05 for all), after surgery compared with preinjury levels. However, these declines were not different from similar declines found in age-matched controls who did not undergo UCL reconstruction.¹⁴ The strength of the conclusions reached in these studies may be limited by inconsistencies in the reporting of outcomes, including advanced performance statistics, and the varied quality of evidence available in the literature.

Advanced performance statistics, such as Wins Above Replacement (WAR) and Runs Above Replacement (RAR) are often used as indicators of a player's overall performance, especially when making decisions regarding free agent contracts and player bonuses. However, few studies have adequately considered their role in evaluating pitcher performance after UCL reconstruction.^3,13,19 Given the potential inaccuracies in public perceptions of outcomes after UCL reconstruction, providing reliable reporting of outcomes can provide accurate counseling and set realistic expectations to patients considering surgery.¹⁵ We assessed performance metrics in MLB pitchers before and after UCL reconstruction utilizing a large publicly available database. Primary metrics included (1) WAR and RAR among MLB pitchers; as well as (2) fastball velocity (mph) following return from UCLR.

2 Methods

All major league baseball (MLB) pitchers who had undergone UCLR between 1983 and 2022 was obtained from a publicly available database: FanGraphs (www.fangraphs.com). Inclusion criteria included: (1) pitchers who appeared in ≥10 MLB games during a single season and (2) a minimum of 24 months’ follow-up. Exclusion criteria included: nonpitcher position players, minor league players, and prior UCLR. A total of 185 pitchers met inclusion criteria. The UCL players were identified using similar methods to those of previous studies, including Baseball Prospectus (http://www.baseballprospectus.com), Baseball Heat Maps (http://www.baseballheatmaps.com), as well as publicly available team press releases..^4,6,14

Each player who met the inclusion criteria was assessed on return to MLB, including time to return, competition following UCLR. Data was collected 1-year before UCLR, 1-year after surgery, and 2-years after surgery. Additionally, the average of the available time points “before surgery” and “after surgery” were gathered. Data collected included: games played, innings pitched, earned run average (ERA), walks and hits per inning pitched (WHIP), walks per 9 innings (BB/9), strikeouts per 9 innings (K/9), wins above replacement (WAR), and runs above replacement (RAR). WAR is the calculation multiple variables to give a numerical value of a player with regards wins above a replacement player; >8 is MVP, >5 all-star, >2 starter, 0–2 reserve, and <0 replacement. RAR weighs heavier on runs than wins and represents the number of runs a player is superior to a replacement-level player. We also collected the percentage of each pitch thrown including fastball, slider, cutter, curveball, and change up. All statistical analyses were performed using R Studio (Statistics Department of the University of Auckland, New Zealand) with significance set as p < 0.05.

3 Results

A total of 357 incidences of Tommy John surgery in MLB players were identified from the database from 1983 to 2012. There were 276 of 357 players (77.3 %) who returned to play after UCL reconstruction. 59 patients were excluded for reasons of playing less than 24 months in MLB after UCLR, and 32 patients were excluded because they appeared in <10 MLB games during a single season. After inclusion and exclusion criteria were applied, there were a total of 185 pitchers remained to be analyzed in the study.

4 Discussion

Pitchers in the MLB have large financial incentives to maintain their health and perform at their expected levels.²¹ Many players and coaches believe that UCL should be performed on players without injuries to enhance performance. The annual number of UCL reconstructions in MLB pitchers has steadily increased from the early 1970s.^4,12 However, prior studies demonstrated mixed findings regarding changes in-game statistics and without emphasis on advanced performance statistics before and after UCLR, warranting further investigation. The major findings in our study demonstrated that MLB pitchers who returned from UCLR had lower WAR and RAR at 1 and 2 years as compared to pre-UCLR levels. Additionally, fastball velocity was not found to change significantly between the two cohorts.

Several studies showed inconsistent results regarding competitive outcomes after UCLR. Thomas et al. reviewed 29 studies of MLB pitchers and found that although professional pitchers experienced decreased workloads and fastball usage, pitchers had ERA, WHIP, and average fastball velocity statistics equal to or better than controls. The authors attributed these findings to strengthening during the rehabilitation process, integrity of the surgical procedure, and decreased workloads after UCL reconstruction, which may limit pitcher fatigue.¹⁸ Our study similarly showed no change ERA, WHIP, and average fastball velocity. However, the systematic review did not examine advanced performance statistics or pitch type, which was a focus of our analysis. Another analysis reviewed 14 studies of 1520 pitchers but found major heterogeneity in the findings, in regard to ERA and fastball velocity. The authors acknowledged several shortcomings in the nature of the studies, including inconsistency in the findings and uncertainty whether these changes of in-game statistics are clinically meaningful. In addition, data collection time points varied for each study, ranging from career averages to 3 seasons before injury and after return to MLB. Furthermore, the authors showed a large variation in the average time to return to pitching, ranging from 11.5 to 20.5 months, which may be due to differences in definitions of return to sport.⁵

Fastball velocity was similar in MLB pitchers who returned from UCLR in our study. This may be attributed to the biomechanical stability of a reconstructed ligament relative to its native strength. In a cadaveric study examining biomechanical properties of the UCL, Ahmad et al. compared stiffness and stability in 10 matched elbows, either intact, released or reconstructed UCL. They found that the UCL in native elbows conferred an average stiffness of 42.81±11.6 N/mm, significantly higher than that in the reconstructed UCL (20.28±12.5 N/mm).² Multiple studies support our findings that fastball velocity remained insignificantly changed following UCLR. In a study of 56 MLB pitchers were underwent UCLR between 2011 and 2012, McKnight et al. assessed multiple pitching metrics upon return to MLB play. They found an similar fastball velocities preoperatively compared to post-UCLR (p = 0.194).¹⁶ In a similar study assessing 46 MLB pitchers from 2008 to 2015, Gray et al. also found no significant changes to fastball velocity, comparing preoperative and postoperative measurements at 12–24 months and 24–36 months (93.19 ± 5.75 vs. 92.92 ± 5.17 vs. 92.95 ± 5.08, p > 0.30). Our study corroborates these prior studies demonstrating insignificant fastball velocity improvements, using compiled data from 1988 to 2022.⁸

Few studies in the literature examine advanced performance metrics, such as WAR and RAR, following UCL reconstruction. Selley et al. examined 148 MLB pitchers undergoing UCL reconstruction and demonstrated that pitchers had worse WAR and lower win probability added (p < 0.05) after return to play. We found similar findings in regard to WAR and RAR at 1-year and 2-years after UCL reconstruction.¹⁷ The authors did not study pitch type or examine outcomes by years after surgery, which provides a more comprehensive view of player performance. Whiteside et al. found that greater average pitch speed, small repertoire of pitches, fewer days between games, smaller stature, and greater average pitch count per game were predictors of UCL reconstruction.²⁰ Landsdown et al. studied 129 pitchers and showed that 80 MLB pitchers produced fewer WAR relative to their preinjury state with a more pronounced decline in pitchers who were more valuable prior to injury.¹¹ Keller et al. demonstrated in 83 MLB pitchers that pitch velocity was not a risk factor for UCL reconstruction but MLB pitchers who pitch a higher percentage of fastball may be at an increased risk for UCL reconstruction.¹⁰ Our study is one of the few studies in the literature that examined pitch after UCLR and we found that pitch type did not change before and after surgery, which is consistent with a previous study.⁹

Few studies find nonsignificant declines in advanced performance metrics but in select patient populations. Marshall et al. examined pitching performance following 33 revision UCL reconstruction in MLB pitchers and revealed nonsignificant declines in WAR (UCL-R: 0.25, CTL: 0.62, P = 0.06) and RAR (UCL-R: 3.26, CTL: 6.91, P = 0.07).⁹ These findings were corroborated in 35 MLB position players as well.⁷ While these studies introduced novel patient populations, they may suffer from small patient numbers and be underpowered to detect a difference in advanced performance metrics. These statistics allowed of a comparison of pitcher value independent of external factors that may influence performance and offer better insight into individual performance.²⁰

The authors acknowledge potential limitations to the study. The study relied on publicly available information which may limit the accuracy of the reporting. We did not include a control group in the study, which could help mitigate the concern that age-related decline can be a source of the findings. However, the literature has shown that MLB pitchers who undergo UCL reconstruction have a similar age-related declined to various control cohorts of pitchers who did not undergo UCL reconstruction.^3,5 This has also been supported in biomechanical studies that showed similar elbow passive range of motion and biomechanical parameters between MLB pitchers undergoing UCL reconstruction compared to a control group.⁷ We were not able to account for differences in rehabilitation protocols, surgical techniques, and patient factors between the players. Additionally, small changes in performance measurements may not be statistically significant but can represent a meaningful difference on the field. Despite these limitations, the strength of the study lies in the comprehensive assessment of player performance utilizing advanced player statistics following UCL reconstruction in MLB pitchers.

Among MLB pitchers returning to active play following UCLR, WAR and RAR metrics reduced, however fastball velocity remained unchanged. These findings corroborate recent literature regarding this patient population utilizing a larger cohort. Utilizing advanced performance statistics, such as WAR and RAR, provides a more comprehensive view of player performance and works towards improving the reliability of outcomes reported in the literature. Similarities in other metrics including fastball velocity lends further credence to UCLR, when indicated. This can be used as a benchmark in the shared decision making preoperatively as well as influence patient expectations following reconstruction.

Patient consent

No patient consent needed due to retrospective nature and public database.

Ethical approval

IRB exemption due to retrospective nature and public database Authors’ contribution.

CRediT authorship contribution statement

Oliver C. Sax: Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing. Jeremy Dubin: Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing. Hytham S. Salem: Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing, MM, Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Roles/. Joseph Zummo: Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing. Samuel Eaddy: Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing. John V. Ingari: Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing. Craig H. Bennett: Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing. Matthew J. Best: Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing.

Use of AI tool

No use of AI tool.

Funding

None.