Umpire Error Issues Before Video Review
Umpire error issues in NPB had long been a source of frustration for fans and teams. Particularly from the 2000s onward, improvements in television broadcast quality and slow-motion replay technology made umpire errors clearly visible to viewers. In the 2005 Japan Series, a home run call controversy became a major social issue. Determining whether a batted ball hit the top of the fence was extremely difficult with the naked eye, and discrepancies with television footage angered fans. This incident rapidly amplified calls for the introduction of video review. However, there were also strong cautious opinions, rooted in traditional views emphasizing umpire authority and concerns about interrupting the flow of games.
The Gradual Introduction of the Replay Review System
NPB introduced video review in 2010, limited to home run calls. This utilized video footage to determine whether batted balls cleared the fence and whether calls were foul or home run. Multiple calls were overturned in the first year of implementation, demonstrating the system's effectiveness. In 2014, the scope was expanded to include close plays at home plate. Furthermore, in 2016, a 'request system' allowing managers to request replay reviews was introduced on a trial basis. Each team was given 2 request rights per game, with the right not being consumed if the call was overturned.
The Establishment of the Request System and Operational Challenges
Since the request system was officially introduced in 2018, it has become an established part of NPB game operations. In the 2023 season, the request success rate (percentage of overturned calls) was approximately 35%, indicating that a certain number of umpire errors were being corrected through video review. However, operational challenges have also emerged. There is criticism that the time required for review interrupts the flow of games, limitations in judgment due to camera angles and video quality, and dissatisfaction that ball-strike calls are excluded from the request system. Strike zone calls in particular directly affect pitcher and batter performance, leading to growing calls for the introduction of an automated strike zone system (robot umpires).
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The Future of Technology and Umpires
The relationship between technology and umpires in NPB is expected to change further in the future. In MLB, full-scale testing of the Automated Ball-Strike system (ABS) began in the minor leagues from 2024, and its potential introduction in NPB is also being discussed. ABS is a system that measures pitch trajectories using tracking technology and mechanically determines the strike zone. Proponents argue for improved accuracy and consistency of calls, while opponents are concerned about the loss of umpire discretion and the 'human element.' What NPB should aim for is a coexistence model that utilizes technology as a supplementary tool for umpires while respecting their expertise and judgment. Rather than complete mechanization, an approach that seeks the optimal balance between humans and technology is needed.
Tactical Changes Brought by the Request System
The introduction of the request system influenced in-game tactics as well. Managers must strategically decide when to use their request rights, creating a tension between saving them for close late-game situations and deploying them at critical early-game moments. Additionally, changes have been observed in how baserunners slide and how fielders apply tags in plays expected to produce close calls. Catchers have reportedly adjusted their glove positioning to ensure the moment of the tag is clearly captured on camera. Players and coaches now approach plays with video review in mind, and the ability to create clear visual evidence for reviews has come to be recognized as a new tactical skill.
Diversity of Review Systems in International Comparison
Replay review systems have been adopted by professional baseball leagues around the world, but their operational methods differ significantly. MLB introduced its challenge system in 2014, granting managers one challenge per game, with crew chiefs making decisions from the seventh inning onward. The Korea Baseball Organization (KBO) introduced video review in 2009, one year earlier than NPB. Meanwhile, the Chinese Professional Baseball League (CPBL) in Taiwan fully implemented the system in 2016. Each league's system differs in the scope of reviewable plays, time limits for review, and overturn rates. NPB's request system has distinctive features, including a broad range of reviewable plays and the non-consumption of request rights when a call is successfully overturned.
Fan Experience and Video Review
While video review improves the fairness of games, it has also transformed the fan experience at stadiums. During request waiting periods, replay footage is repeatedly shown on large stadium screens, giving spectators a sense of participation in the review process. The sight of fans in the stands cheering or protesting while watching replays has formed a new spectating culture. However, in cases where reviews take more than three minutes, there are criticisms that the stadium atmosphere stagnates and the tempo of the game suffers. Stadiums have developed entertainment during request periods, such as quiz segments and highlight videos, as the balance between the review system and baseball as entertainment continues to be explored.