The Basic Structure of NPB's Registration System
NPB's player registration system consists of a two-tier structure: roster registration and active player registration. Roster registration sets the upper limit of players a team can hold, currently capped at 70 per team. Active player registration (the so-called bench roster) defines the players who can actually participate in games, currently set at 29 (13 pitchers, 16 position players) as the standard. This two-tier structure is a rational mechanism separating team player holdings from game operations, but the numbers have evolved over time. The roster registration limit is directly connected to team management scale and player development policies, with expansion meaning increased personnel costs. The active player registration limit directly affects tactical breadth in games, particularly having significant impact on pitcher deployment.
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Historical Evolution of Bench Roster Sizes
NPB's bench roster sizes have been gradually expanded throughout the league's history. The bench roster of 25 players at the start of the two-league system in the 1950s came under expansion pressure as pitcher specialization advanced. By the 1990s, the division of pitcher roles into starters, middle relievers, and closers became clear, increasing the number of pitchers needed in the bullpen. In 2005, the active player registration was expanded from 25 to 28, and further to 29 in 2024. This expansion was supported from the perspective of preventing pitcher overwork and protecting player health. However, there is also criticism that expanding bench rosters leads to longer game times. The argument is that increased pitching changes slow game tempo and break spectator concentration. Setting bench roster sizes is built on the balance between the conflicting demands of protecting player health and maintaining game quality.
Introduction of the Development Player System and Roster Expansion
The development player system introduced in 2005 added a new dimension to NPB's registration framework. Development players are not included in the 70-player roster limit and can be independently held by each team. This system was created to provide second chances for players not selected in the draft or removed from the active roster. The greatest success stories of the development player system are the Giants' Tetsuya Yamaguchi and SoftBank's Kodai Senga. Their presence as development draft picks who thrived at the first-team level and grew into representative players proved the system's effectiveness. However, the development player system has challenges. Some teams stockpile large numbers of development players, drawing criticism over the significant difference in treatment compared to roster players. Development players' minimum guaranteed salaries are set low, and improvement of working conditions is being demanded.
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The Future of Registration Systems and Comparison with MLB
NPB's registration system has unique characteristics compared to MLB's roster system. MLB expanded its active roster to 26 in 2020, with expansion to 28 in September. NPB's 29-player active registration is comparable to MLB's level. A future challenge being discussed is the flexibilization of pitcher and position player registration slots. The current system fixes 13 pitchers and 16 position players, but there are calls for transitioning to a flexible system allowing allocation changes based on team strategy. Additionally, the emergence of two-way players has made the distinction between pitchers and position players increasingly ambiguous, potentially necessitating a fundamental review of the registration system. NPB's registration system requires delicate system design that simultaneously pursues three goals: protecting player health, diversifying team strategies, and maintaining game quality.