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.
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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.