The Developmental Player System (育成選手制度, Ikusei Sensyu Seido) is a system that allows players to be held for the purpose of training players separately from the 70 registered players under control of each team created in the fall of 2005 at Nippon Professional Baseball (NPB).^[1]

Summary

This system was established in 2005 to create an environment in which amateur players can newly play in the situation where company-owned amateur baseball teams were being abolished one after another.^[2] A Developmental player (育成選手, Ikusei Sensyu) is a player who aims to improve baseball skill training and manner training in order to aim for registered players under control, that is eligible to participate in NPB's first league official game (Central League, Pacific League, Interleague play (NPB)). (Regulations for NPB Developmental players, Article 2)^[3]

A developmental players include players drafted as rookies (e.g. Yusuke Kosai and Michitaka Nishiyama, drafted developmental player who were first signed as a registered player under control in 2006.), foreign players signed as developmental players (e.g., Raidel Martínez, Liván Moinelo.), players drafted as registered players under control but re-signed with a team as developmental players due to their abilities (e.g., Kenta Kurose - Re-signed as a registered player under control.), players who became free agents with their former team and signed with another team (e.g., Masaru Nakamura, Kouya Fujii - Re-signed as a registered player under control.), and players who were removed from the registration of players under control and re-signed as a developmental player due to treat injuries (e.g., Takuya Kuwahara, Hiroya Shimamoto.). There is an argument that eliminating players who cannot play due to injury from the registration of players under control and re-signing them as developmental players will protect their careers. On the other hand, the use of the developmental players system instead of the Major League Baseball (MLB) Injured list system is criticized as contrary to the original principle of this system, which is to open the door to amateur players and develop them.^[4] The oldest player to become a developmental player is Soichi Fujita, who signed in 2011 at the age of 39. The longest period as a developmental player was Kousuke Naruse [jp]'s eight seasons (2011-2018) as of the 2022 season.

Regulations for Developmental Player

Player Rules

• Basically, they are not allowed to participate in official NPB games. However, up to five players per team per game are allowed to play in the Eastern League and Western League for developmental players.^[1] Other players play in practice games for the second squad. And make up the third squad, like the Yomiuri Giants and the Fukuoka SoftBank Hawks, and play in games against independent league teams such as the Shikoku Island League Plus and Baseball Challenge League, corporate amateur teams, and university teams.^[5][6] The Hawks’ｓ third squad play more than 100 games a year.^[7] But there is a difference in contract between a registered players under control and a developmental players, but unlike the relationship between major leaguers and minor leaguers in Major League Baseball, they are players on the same team. They use the same practice facility and player dormitory.^[8]
• The contract is for a maximum of three years, but after the fourth year, the player can become a free agent once and sign with the same team again.^[1] After the fourth season, the contract will be for one year, and after each season, the NPB will announce the free agent status, after which the player can re-sign.^[9] This measure is intended to increase the player's chances of signing a registration of players under control contract, and during the free agent period, he can negotiate with other teams. In 2019, Hiroki Hasegawa moved from the Fukuoka Softbank Hawks to the Tokyo Yakult Swallows.^[10] A one-year contract is also possible for a registered players under control to re-sign as a developmental player after a free agent announcement has been made. (Regulations for NPB Developmental players, Article 10)^[3] Players who have not been under contract for three seasons will be placed on the roster of pending developmental players, and other teams will not be able to negotiate with them.^[11]
• The minimum salary is 2.4 million yen and 3 million yen is paid as a preparation fee when drafted.^[1] However, since there is no cap on annual salary, some teams sign players at higher salaries, and players who are re-signed as developmental players from a registered players under control often maintain the salary level of a registered players under control.^[12][13] The number on the back of the uniform of the developmental players will be a three-digit number (e.g. 110, or 001).

Regulations for teams that own developmental players

• The deadline for re-signing a developmental player as a registered players under control is from the end of the season to July 31st during the following season, as stated above.However, it is not permitted to change from a registered players under control to a developmental contract during the season.^[1]
• A developmental players can only be owned by teams with at least 65 controlled players as of July 31, and teams with fewer than 65 controlled players cannot own them. However, if a team reports to the Executive Committee that it has re-signed a developmental player as a controlled player or acquired a new controlled player to bring the number of controlled players to 65 or more, and if this is approved, the team may retain the developmental player. (Regulations for NPB Developmental players, Article 3)^[3] There is no limit to the number of developmental players owned.^[14] Some teams, such as the Yomiuri Giants and Fukuoka Softbank Hawks, have more than 30 players and use a 3-team system, while others, such as the Hanshin Tigers, have only a few players, depending on the team's policy.^[15][16][17] The Fukuoka SoftBank Hawks have selected 14 new developmental players in the 2022 draft to implement a four-team system from the 2023 season.^[18]

Developmental Players Draft Meeting

• If the total number of players selected at the end of the Rookie Player Selection Conference has not reached 120, a Developmental Players Selection Meeting will be held with the participation of the teams that wish to participate.^[19]

Developmental players trade

• Article 11 of the Nippon Professional Baseball Developed Player Regulations states that a trade of a developmental player held by July 31 is allowed, but as of the 2022 season, there are no examples of such a trade.^[3]

Outcome

The developmental player system, which began in the 2005 season, has been successful in producing major players for each team. (e.g. Yoshiki Sunada, Yuji Nishino) The Yomiuri Giants, who have been working on this system since early on, have signed more than 50 developmental players as their registered players under control as of the 2022 season. The Fukuoka Softbank Hawks have also signed 40 developmental players as their registered players under control, and have produced players like Kodai Senga and Takuya Kai who have won league titles and awards and represented Japanese baseball on the national baseball team.^[20] The Hokkaido Nippon-Ham Fighters, which had been reluctant to acquire developmental players, drafted a player as a developmental player for the first time in the 2018 draft.^[21] In the 2022 draft, 51 players will be selected as developmental players, the largest number in history, and the acquisition of developmental players is a growing trend.^[22]

Current developmental player rosters

Central League

Pacific League

List of developmental players for the Nippon Professional Baseball

• List of developmental players for the Nippon Professional Baseball (wikipedia Japanese version.)