MLB Injury Index: Assessing the impact of injuries on every team in the league
The Bronx’s suffering was epitomized by the onslaught of injuries, causing pain both figuratively and literally. As players succumbed one by one, the Yankees found themselves plummeting in the American League standings. Despite preseason optimism, the league’s most illustrious franchise stumbled into fourth place, barely scraping past the .500 mark they had consistently surpassed for over three decades.
Had this outcome not felt so familiar, perhaps the forgiving New York crowd would have dismissed it as mere misfortune and moved on. However, the frustration lingered into the offseason, as bad luck seemed insufficient to explain the season’s woes. The entire campaign felt like a repetitive narrative, a déjà vu for Yankees fans.
To quantify this phenomenon, we developed the Injury Index (details of which are outlined below). This tool aims to assess the frequency of each team’s use of the injured list (IL) over recent seasons and estimate the production lost due to players spending more time in the trainer’s room than on the field. We also applied this analysis to each team’s current roster to gauge their susceptibility to injuries in the upcoming 2024 season.
Tier 1: Heavy IL Use
(Note: Teams in this tier have an Injury Index at least half a standard deviation above average.)
1. New York Yankees (Injury Index: 111.5)
2. Tampa Bay Rays (110.2)
3. Los Angeles Dodgers (110.0)
4. Atlanta Braves (106.7)
5. Minnesota Twins (106.6)
6. Houston Astros (105.5)
Injuries are an inherent part of every team’s season planning, with each team inevitably facing them. However, the extent of these injuries becomes a distinguishing factor. On average, teams lost approximately 5.5 wins above replacement (WAR) last season, with the Yankees enduring an estimated loss of 14.7 WAR due to IL placements—9.2 WAR above the league average. The second-highest figure belonged to the Twins at 5.2 WAR.
The Injury Index was calculated using IL usage data from Spotrac dating back to 2015. This data includes player details, nature of injuries, and the number of days spent on the IL during a season. By estimating each player’s baseline WAR projection, we calculated the “Estimated WAR Lost” for each entry. The index tallied these figures for each team across the past five seasons, with more recent seasons weighted more heavily. The higher the index, the greater the impact of injuries on the team.
The Yankees’ one-season Injury Index of 128 was among the highest of the past five years. Notably, their losses were distributed unusually evenly between position players (second highest in the majors) and pitchers (highest in baseball).
This pattern is not isolated, as evidenced by the Yankees consistently ranking high in the Injury Index. Their ranking in recent seasons includes second, fourth, fifth, 18th, and first place in 2019, 2020, 2021, 2022, and 2023, respectively. The Yankees, along with the Rays and Braves, have rated above average four times in the past five years.
The reasons for these trends could be manifold. These teams possess talented players, whose absence significantly impacts the team’s performance when they are sidelined. Additionally, they may take on more risk with older players, recognizing the potential impact of their contributions. Other factors may include the intensity of playoff contention, proactive injury prevention strategies, or pitching usage patterns correlating with both high performance and injury risk.
What’s certain is that these teams have suffered more in terms of WAR production loss than others, with the Yankees currently facing the most detrimental combination of injury frequency and the quality of players affected.
