Abstract
Purpose :
Some baseball players undergo laser assisted in situ keratomileusis (LASIK) during their careers, though no study has leveraged sabermetrics to assess hitting outcomes after LASIK. This analysis sought to determine how LASIK impacted Major League Baseball (MLB) hitter plate discipline & league-adjusted performance.
Methods :
MLB players who underwent LASIK and had at least 130 at-bats in the seasons before and after surgery were identified via public records. Individual performance changes were measured and compared across seasons for the plate discipline metrics on-base percentage (OBP), weighted on-base average (wOBA), and walk to strikeout ratio (BB/K), and the baseball sabermetrics weighted runs-created plus (wRC+), weighted runs above average (wRAA), and wins above replacement (WAR).
Results :
In the season prior to LASIK, 43 unique MLB players experienced an average change of -0.009 in OBP (p = 0.118), -0.012 in wOBA (p = 0.081), 0.010 in BB/K (p = 0.763), -9.525 in wRC+ (p = 0.021), -5.633 in wRAA (p = 0.032), and -0.993 in WAR (p = 0.002). In the season after LASIK, players experienced an average change of -0.003 in OBP (p = 0.659), -0.001 in wOBA (p = 0.912), -0.005 in BB/K (p = 0.893), 0.976 in wRC+ (p = 0.833), 3.946 in wRAA (p = 0.833), and 0.541 in WAR (p = 0.155). The season before LASIK, OBP decreased for 63% of players, wOBA decreased for 65%, BB/K decreased for 50%, wRC+ decreased for 70%, wRAA decreased for 65%, and WAR decreased for 70%. The season after LASIK, OBP increased for 44% of players, wOBA increased for 49%, BB/K increased for 46%, wRC+ increased for 49%, wRAA increased for 59%, and WAR increased for 54%.
Conclusions :
This study demonstrated that MLB baseball players have shown a statistically significant drop in the league-adjusted offensive metrics wRC+, wRAA, and WAR in the season prior to LASIK. For plate discipline, OBP & wOBA decreased, albeit not statistically significantly in the season before LASIK, but BB/K increased slightly. This was surprising because it indicates that on average, strikeout rate improved for players by slightly decreasing the season before LASIK. Overall, league-adjusted & plate discipline performance improved after LASIK, but the changes were not statistically significant and may be related to other factors.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.