Concussion Risks in Baseball
Despite being a non-contact sport, baseball presents significant concussion risks from 150+ km/h hit-by-pitches to the head, home plate collisions, outfielder fence impacts, and line drives hitting pitchers. In February 2020, a Rakuten batting-practice pitcher was struck in the head by a batted ball during batting practice and taken to hospital by ambulance, and the next day the team made helmets mandatory for its batting-practice pitchers.
NPB Concussion Protocol
NPB introduced a special concussion measure in 2016. Players removed from the active roster on suspicion of concussion can be re-registered without waiting the usual 10 days if a doctor finds no problem, and the team can register a replacement player in the meantime. Return follows graduated return-to-play programs set separately for pitchers and position players. This weakened the incentive to keep players with a suspected concussion in games because of roster constraints.
Home Plate Collision Rules
NPB adopted collision rules in 2016, prohibiting catchers from blocking the plate and runners from targeting catchers. Previously celebrated as displays of fighting spirit, these collisions caused numerous catcher concussions and fractures before safety was prioritized.
Ongoing Challenges
Long-term concerns include potential CTE from repeated subconcussive impacts, as documented in American football. Remaining challenges include detecting mild concussions, players concealing symptoms, and return-timing decisions. Building a safety-first culture alongside medical protocols remains essential.
Special Roster Provisions and Registration Rules
Even while a player is off the roster under the special measure, the registration days required for free-agent eligibility are not interrupted. The first case was Yakult's Takahiro Imanami, who was removed from the roster in June 2016 and re-registered without waiting 10 days. However, operational challenges persist. Medical facilities at stadiums vary considerably, with some lacking imaging diagnostic equipment. Reaching accurate diagnoses within the limited time constraints of a live game is difficult, requiring a balance between stricter diagnostic standards and operational game management efficiency.
Disparities in Concussion Management Between First and Farm Teams
The benefits of concussion protocols are concentrated among first-team players, with farm-level games often operating under insufficient medical coverage. While team doctors are stationed at first-team games, they may be absent from farm games, forcing trainers to make initial concussion assessments alone. Development-contract players are particularly disadvantaged in accessing medical resources, placed in environments where mild concussions are easily overlooked. Independent leagues face even harsher conditions, with some lacking concussion protocols entirely. Building systems that guarantee equal safety regardless of a player's career stage remains an unresolved challenge.