The End of the Complete Game Era - Numbers Tell the Story of Pitching Changes
Pitcher usage in NPB has changed dramatically over the past 50 years. In the 1970s, starting pitchers' complete game rates exceeded 30%, and it was not uncommon for ace-caliber pitchers to record over 20 complete games per season. Records like Kazuhisa Inao's 42 complete games in 1961 and Masaichi Kaneda's career 365 complete games are numbers inconceivable in the modern era. However, complete game numbers began declining rapidly from the late 1980s. In the 2020s NPB, starting pitchers' complete game rates have fallen below 5%, with virtually no pitchers exceeding 10 complete games per season. Behind this change lies deepened scientific understanding of shoulder and elbow injury risks for pitchers. The concept of pitch count management has permeated, with starting pitcher pitch counts generally managed around 100 pitches. The aesthetics of complete games have retreated before the practical demands of pitcher health and long-term career preservation.
Establishment of Winning Formulas and Elevation of Relief Pitcher Status
From the late 1990s through the 2000s, NPB established relief usage patterns called winning formulas. The division of labor with a setup man in the 7th, bridge in the 8th, and closer in the 9th was widely adopted as a strategy to minimize late-game run-scoring risk. This specialization significantly elevated relief pitcher status. While relievers were once viewed as a landing spot for pitchers who couldn't start, the achievements of pitchers like Hitoki Iwase, Kyuji Fujikawa, and Kazuhiro Sasaki made relief specialists into stars representing the baseball world. However, excessive dependence on winning formulas created the new problem of concentrated workload on specific relievers. Fatigue accumulation and injury risk for relievers appearing in over 70 games per season emerged as the next challenge in bullpen management.
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Evolution of Pitch Count Management and the Emergence of Bullpen Days
Since the 2010s, pitch count management refinement has progressed in NPB. Six days between starts has become standard for starting pitchers, and per-game pitch counts are now strictly managed. This change resulted from MLB pitcher injury research findings spreading to NPB. The increase in Tommy John surgeries in particular strongly reinforced awareness of the need to reduce elbow strain on pitchers. However, reduced innings from starting pitchers means increased bullpen burden. To resolve this contradiction, MLB introduced the opener strategy where a relief pitcher starts and pitches short innings before the intended starter takes over. Some NPB teams have tried the opener, but friction with the value of complete games in Japanese baseball culture has limited its adoption.
The Future of Bullpen Management - Fusion of Data and Health Management
The future of bullpen management lies in the fusion of data analysis and pitcher health management. Technologies for real-time evaluation of pitcher fatigue are developing through TrackMan and biomechanics analysis. Indicators such as velocity decline, spin rate changes, and release point shifts serve as clues for detecting pitcher fatigue and injury precursors. Some NPB teams have begun introducing decision support systems for pitcher substitutions utilizing this data. Bullpen composition itself is also changing. Usage of swingmen who flexibly change roles based on situations is increasing, moving away from the fixed six starters and six relievers format. Pitcher usage is definitively transitioning from an era relying on experience and intuition to an era of data-based scientific management.
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