Fact-checked by Grok 2 weeks ago

Masato Yoshii

Masato Yoshii (吉井 真人, Yoshii Masato; born April 20, 1965) is a Japanese former professional baseball pitcher and coach who played 23 seasons in (NPB) from 1985 to 2007, including five years in (MLB) from 1998 to 2002, and later served as a pitching coach for multiple NPB teams before managing the from 2023 to 2025. Yoshii began his professional career with the Kintetsu Buffaloes in 1985, where he spent a decade as a reliable starter and reliever, compiling a 90-90 record over his NPB tenure with an overall of 4.11, highlighted by a career-best 13 wins in 1997 with the Yakult Swallows. After stints with the Yakult Swallows (1995–1997) and a brief return to the (2003–2007), including a mid-2007 trade to the , he retired at age 42 following a 1-9 season impacted by injuries. His NPB contributions included 24 saves in 1988 and multiple complete games, establishing him as a durable right-handed known for control rather than overpowering velocity. In MLB, Yoshii debuted at age 32 with the in 1998, posting a 9-3 record and 3.93 ERA in his rookie year as part of a rotation that helped the team reach the . He appeared in 162 games across five seasons with the Mets (1998–1999), (2000), and (2001–2002), finishing with a 32-47 record, 4.62 ERA, and 447 strikeouts over 757.1 innings, often struggling with the hitter-friendly environments of and . After retiring, Yoshii transitioned to coaching, serving as pitching coach for the (2008–2012, 2016–2018), (2015), and (2019–2021), where he helped develop young talent and contributed to Japan's as pitching coach for the national team at the . Appointed manager of the in 2023 succeeding , he led the team for three seasons but resigned on October 5, 2025, taking responsibility for their last-place finish in the —their worst since 2017.

Early life and education

Childhood and amateur career

Masato Yoshii was born on April 20, 1965, in Aridagawa, a rural town in , . Yoshii's introduction to occurred in high school at Minoshima High School in Wakayama, a institution with a storied history in amateur , including multiple Koshien tournament victories. There, he honed his initial pitching skills and emerged as a key player, participating in the prestigious (Koshien) twice during his tenure, helping lead the team in regional tournaments. Earned the nickname "Oiyan" during his early playing days, a moniker reflecting his straightforward personality influenced by the Kansai region's direct communication style. Following graduation, Yoshii transitioned to after being selected by the Kintetsu Buffaloes in round of the 1983 NPB , signing with the team for a faster path to the major roster.

Higher education and development

After graduating from high school, Yoshii entered directly, selected by the Kintetsu Buffaloes in round of the 1983 NPB without pursuing or university-level play, and honed his skills through the team's developmental system leading to his professional debut in 1985. In 2013, Yoshii enrolled in a master's program in at the , specializing in theory to deepen his understanding of the scientific principles underlying pitching and athlete . He completed the degree in 2016, focusing on coursework that emphasized objective analysis of sports performance. Yoshii's studies provided insights into methodologies and , which he later reflected upon to better comprehend the biomechanical and factors that shaped his own professional pitching career. In a 2024 interview, he highlighted the value of , noting how the program shifted his perspective from experiential knowledge to a more evidence-based approach, enhancing his personal growth by integrating intellectual pursuits with his expertise. This educational experience underscored the benefits of balancing athletic demands with academic exploration, particularly in areas related to pitcher conditioning and performance optimization.

Professional playing career

NPB career (1985–1997)

Masato Yoshii made his professional debut on September 16, 1985, with the Kintetsu Buffaloes of the , appearing in relief and pitching one scoreless inning against the Seibu Lions. He spent his initial years primarily as a reliever, appearing in just four games across 1985 and 1986 with high ERAs in limited innings, before posting a 2-1 record and 4.75 ERA in 13 appearances in 1987. These early seasons reflected his adjustment to , with Yoshii logging only 41.1 innings over his first three years. Yoshii's breakout came in 1988, when he transitioned into a prominent relief role for the Buffaloes, achieving a 10-2 record with 24 saves and a 2.69 ERA over 80.1 innings in 50 games. This performance earned him the Pacific League Fireman of the Year award, recognizing him as the league's top reliever. He followed with another strong relief season in 1989 (5-5, 20 saves, 2.99 ERA in 47 games), but began shifting toward starting duties by 1990, where he recorded 8-9 with 15 saves in 45 appearances. Appearances dropped in 1991 and 1992 due to adjustment challenges and limited opportunities, totaling just 30 games with a combined 3-1 record and 3.10 ERA. Yoshii joined the Kintetsu rotation more consistently in 1993, going 5-5 with a 2.67 in 22 games (13 starts), before a tougher 1994 season where he posted 7-7 and 5.47 in 19 starts amid struggles with command. Traded to the Swallows of the before the 1995 season in exchange for outfielder , he adapted quickly as a starter, recording double-digit wins in each of his three years there: 10-7 with a 3.12 in 1995, 10-7 and 3.24 in 1996, and 13-6 with a 2.99 in 1997 while contributing to Yakult's championship, including a strong start in Game 3. Through 1997, Yoshii compiled a 73-51 record with a 3.66 , 61 saves, and 627 strikeouts in 310 games across the Kintetsu Buffaloes and Yakult Swallows, showcasing steady growth from reliever to reliable starter despite periodic setbacks like his 1994 dip. Following his strong 1997 campaign, Yoshii entered free agency and signed a one-year contract with the in the 1997-1998 offseason, valued at $200,000 base with incentives up to $1 million, marking his pursuit of .

Major League Baseball career (1998–2002)

Masato Yoshii signed with the New York Mets as a on January 13, 1998, marking his transition to after a distinguished career in Japan's . He made his MLB debut on April 5, 1998, starting against the at , where he pitched seven innings in a no-decision. In his rookie season, Yoshii posted a 6-8 record with a 3.93 ERA over 29 starts, logging 171.2 innings and striking out 117 batters, providing reliable back-end rotation support for a Mets team that finished second in the with an 88-74 record, just one game out of the playoffs. Notable outings included a career-high 10 strikeouts in an interleague win against the New York Yankees on June 28. Yoshii's performance improved in 1999, as he went 12-8 with a 4.40 in 29 starts, accumulating 174 innings and 105 strikeouts while allowing 25 home runs. His contributions included a against the on May 21, helping anchor the Mets' rotation during their late-season surge. His contributions were instrumental in the Mets securing the with a 97-65 record, though he did not appear in the postseason. On January 14, 2000, the Mets traded Yoshii to the Colorado Rockies in exchange for pitcher Bobby Jones and prospect Lariel Gonzalez, aiming to shed his $3 million salary and acquire depth. With the Rockies, Yoshii struggled significantly at due to the high altitude, which exacerbated his fly-ball tendencies and led to a 5.85 in home games; overall, he finished 6-15 with a 5.86 in 29 starts, 167.1 innings, and 88 strikeouts. Released by the Rockies on March 28, 2001, Yoshii signed as a with the later that month. In 2001, he appeared in 42 games (11 starts) with a 4-7 record and 4.78 over 113 , transitioning to a role. The following year, 2002, saw him make 20 starts among 31 appearances for a 4-9 record and 4.11 in 131.1 with 74 strikeouts, but his effectiveness waned late in the season; his final MLB game was on September 11, 2002, against the Florida Marlins, after which the Expos granted him an unconditional release on December 4. Over his five MLB seasons, Yoshii compiled a 32-47 record with a 4.62 , 447 strikeouts, and 757.1 in 162 games (118 starts), often facing challenges from language barriers that hindered communication with coaches and teammates, extensive travel across larger U.S. ballparks compared to Japan's more compact venues, and adapting to varied pitching conditions. Off the field, Yoshii worked to overcome these hurdles by studying English and actively engaging with fans and teammates, such as during Mets photo days where he was noted for his approachable interactions despite limited fluency.

Return to NPB (2003–2007)

After being released by the Montreal Expos following the 2002 season, Masato Yoshii signed a one-year contract with the BlueWave of Nippon Professional Baseball's on January 7, 2003, marking his return to after five years in . In his first season back, Yoshii transitioned back to a starting role but faced challenges adjusting, posting a 2-7 record with a 6.51 over 24 appearances, including 12 starts and 76 innings pitched. The 2004 campaign brought further difficulties due to injuries and inconsistency, limiting him to just three games (one start) with , where he went 0-1 with a 17.18 in 3⅔ innings. Yoshii rebounded in 2005 with the newly merged , re-establishing himself as a reliable starter by going 6-5 with a 4.03 in 15 starts, allowing only nine walks across 73⅔ while demonstrating improved command and resilience following his MLB tenure. He built on this momentum in 2006, delivering a solid performance with a 7-9 record and 3.81 in 19 starts over 101⅔ , contributing to team stability as a presence on the pitching staff. Entering the 2007 season at age 42, Yoshii started strongly for , securing his lone win of the year on April 25 against the , where he pitched eight and allowed eight unearned runs en route to the victory. However, his form dipped later, leading to a 1-6 record and 5.75 in 40⅔ before the Buffaloes traded him to the on June 28 in exchange for Koji Hirashita, as shifted toward younger players. With , Yoshii made four starts but struggled, going 0-3 with a 13.14 in 12⅓ , finishing the year 1-9 overall with a 7.47 across 14 starts. Over his five seasons back in NPB (2003–2007), Yoshii compiled a 16-31 record with a 5.47 in 75 appearances (61 starts), totaling 308 while serving as a mentor to younger pitchers through his experience bridging and styles. He retired at the end of the 2007 season after 24 professional years, concluding his playing career with the .

Post-playing career

Coaching roles

Following his retirement from professional baseball after the 2007 season, Masato Yoshii transitioned into by joining the as their pitching coach in 2008. He held the position through the 2012 season, marking the start of a lengthy involvement with the organization that resumed from 2016 to 2018. He also served as pitching coach for the in 2015. From 2019 to 2021, Yoshii was the pitching coach for the . Additionally, he contributed to Japan's gold medal victory as pitching coach for the national team at the . Yoshii's coaching philosophy centered on pitch efficiency and , drawing from his experiences in both and . He implemented a blend of styles by using a during bullpen sessions to time pitchers' mound work, typically limiting sessions to 25 minutes to simulate game conditions while keeping pitch totals below 100 and avoiding overuse among the young staff. During his tenures with the Fighters, Yoshii played a key role in developing emerging pitchers, particularly those with strong velocity but control challenges, helping them refine mechanics for better command. His contributions supported the team's postseason runs, including their victory over the . These experiences were informed by Yoshii's academic pursuits at the , where he earned a in focused on coaching theory starting in 2013. He has emphasized data-driven training in interviews, applying scientific principles to optimize pitcher workloads and .

Managerial career

Masato Yoshii was appointed manager of the on October 7, 2022, succeeding who had resigned suddenly after the 2022 season; this marked Yoshii's first role as a manager at the age of 57. During the 2023 season, Yoshii led the to second place in the , implementing strategies centered on development and fostering balanced lineups to maximize team versatility. In 2024, the team finished third under his guidance, continuing to emphasize gradual integration of young to build endurance and prevent overuse, drawing from Yoshii's experience as a former pitching coach. The 2025 season, however, saw the drop to last place in the , hampered by a string of key player injuries that disrupted roster stability. Yoshii faced significant challenges in managing injuries, such as that affecting veteran infielder Takashi Ogino, which forced frequent roster adjustments and lineup experiments to maintain competitiveness. He placed a strong emphasis on player education and mental preparation, informed by his master's degree in coaching theory from , advocating for evidence-based methods to enhance players' long-term careers and decision-making under pressure. On October 5, 2025, Yoshii announced his after three seasons, citing the team's disappointing results as the primary reason.

Playing style and legacy

Pitching repertoire and mechanics

Masato Yoshii, a right-handed , relied on a centered around control and movement rather than overpowering throughout his . His primary pitches included a typically clocked in the low-to-mid 90s mph (rarely exceeding 90 mph), a sinker, and a , which he used to induce weak contact and ground balls. He also incorporated a split-fingered as his standout offering for deception. Yoshii's mechanics featured a smooth, efficient delivery that prioritized precision over arm speed, allowing him to maintain command within the while minimizing strain on his arm. Standing at 6 feet 2 inches and weighing 210 pounds, his sturdy build contributed to his durability, enabling him to pitch deep into games without frequent injuries when his mechanics remained sound. On the mound, he exhibited a calm, patient demeanor that disrupted hitters' timing, often working methodically to set up off-speed pitches. Early in his professional career, Yoshii honed his skills as a reliever, focusing on high-leverage situations like closing games in , where his and combination proved effective for quick outs. By the early , he transitioned to a starting role, building stamina through his efficient mechanics to handle fuller outings. Upon arriving in in 1998, he adapted by refining his for the wider and more aggressive hitters, emphasizing off-speed movement to complement his .

Achievements and impact

Masato Yoshii earned the Relief Pitcher of the Year award in 1988 while with the Kintetsu Buffaloes, recording 24 saves and a 2.69 in 50 appearances. During his time with the Yakult Swallows from 1995 to 1997, he achieved double-digit wins in each season, posting records of 10-7, 10-7, and 13-6 respectively, with ERAs ranging from 2.99 to 3.24. In 2006, while pitching for the , Yoshii secured victories against all 12 NPB teams, a rare accomplishment marking him as only the fifth player to achieve this feat in league history. Yoshii's professional career spanned 23 seasons from 1985 to 2007 across NPB and MLB, totaling 89 wins, 82 losses, and 62 saves with a 3.86 in 385 NPB games. He stands as one of six pitchers in baseball history to record a win after turning , achieving his final victory in 2007 at age with the . This longevity highlighted his durability and adaptability, bridging eras in both and . As one of the early Japanese pitchers to transition to MLB following Hideo Nomo's pioneering 1995 debut, Yoshii joined the in 1998, inspired by Nomo's success to pursue his own major league aspirations. His five-year MLB tenure, including stints with the Mets, Rockies, and Expos, contributed to growing cross-cultural exchanges between NPB and MLB, paving the way for subsequent Japanese imports. In his post-playing career as a coach and manager, Yoshii has emphasized education in sports development, earning a in from University in 2013 and applying scientific coaching principles to nurture talents like Roki Sasaki at the Lotte Marines. Yoshii's approachable demeanor earned him the nickname "Oiyan," reflecting his friendly, relatable style that endeared him to fans and teammates. His contributions to the , where he played from 2003 to 2007 and later served as manager from 2023 to 2025—resigning on October 5, 2025, following the team's last-place finish in the —have solidified his legacy within the franchise, blending on-field performance with off-field mentorship to foster team culture and player growth.

References

  1. [1]
    Masato Yoshii Stats, Height, Weight, Position, Rookie Status & More
    Position: Pitcher ; Bats: Right • Throws: Right ; Born: April 20, 1965 in Arita-gun, Japan jp ; High School: Minoshima (Wakayama, Japan) ; Debut: April 5, 1998 (Age ...
  2. [2]
    Masato Yoshii Japanese Leagues Statistics - Baseball-Reference.com
    Position: Pitcher ; Bats: Right • Throws: Right ; Born: April 20, 1965 in Arita-gun, Japan jp ; High School: Minoshima (Wakayama, Japan) ; Last Game: September 11, ...
  3. [3]
    Masato Yoshii - Montreal Expos Starting Pitcher - ESPN
    Starting Pitcher ... Birthdate ... 4/20/1965 ... BAT/THR ... Right/Right ... Birthplace ... Osaka, Japan ... Follow ... Career Stats ... W-L ... 32-47 ... ERA ... 4.62 ... K ... 447 ... WHIP.
  4. [4]
    Masato Yoshii - BR Bullpen - Baseball-Reference.com
    Aug 6, 2025 · Yoshii began 2007 with a 1-6, 5.75 record, then was traded in late June to the Chiba Lotte Marines for backup OF Koji Hirashita. He was 0-3 ...
  5. [5]
    Masato Yoshii Career Stats - MLB - ESPN
    MasatoYoshii · Birthdate. 4/20/1965 · BAT/THR. Right/Right · Birthplace. Osaka, Japan. Follow. Career Stats. W-L. 32-47. ERA. 4.62. K. 447. WHIP.
  6. [6]
    Masato Yoshii Stats, Age, Position, Height, Weight, Fantasy & News
    Masato Yoshii Bio · Fullname: Masato Yoshii · Born: 4/20/1965 in Osaka, Japan · High School: Minoshima, Wakayama, JPN · Debut: 4/05/1998.
  7. [7]
    Yoshii to step down as Marines manager after last-place finish
    Oct 5, 2025 · The Lotte Marines announced Sunday that Masato Yoshii is stepping down as manager of the Pacific League club at the conclusion of the ...<|control11|><|separator|>
  8. [8]
    Lotte announced that manager Masato Yoshii had offered his ...
    [Lotte] Manager Yoshii Masato announced that his resignation was accepted by the 4th. Head coach Saburo is the likely successor. Sports Hochi. 2025.10.5(日) 10: ...
  9. [9]
    Minoshima High School - BR Bullpen - Baseball-Reference.com
    Nov 1, 2025 · Minoshima High School is located in Arida, Wakayama. They won the Summer Koshien in 1979 and the Spring Koshien in 1970, 1977 and 1979.
  10. [10]
    [Yamashita Norito, Lotte] He played at Koshien with Yoshii Masato at ...
    Aug 16, 2024 · [Yamashita Norito, Lotte] He played at Koshien with Yoshii Masato at Minoshima High School. After... Auto-dubbed. 7K views · 1 year ago
  11. [11]
    Pro Baseball Stars
    Mar 29, 2008 · Masato Yoshii Born Apr.10, 1965. 185 cm. tall and weighs 88 ... He was the 2nd draft pick for the Kintetsu Buffaloes in 1983. 1988 ...
  12. [12]
    Baseball manager Masato Yoshii touts benefits of higher learning
    Mar 15, 2024 · For Lotte Marines manager Masato Yoshii, going back to school provided the insight and perspective he felt he needed for the latest chapter ...Missing: Minoshima Koshien
  13. [13]
    Mr. YOSHII Masato (Head Coach, Chiba Lotte Marines) - YouTube
    Aug 7, 2023 · YOSHII Masato 2016 Completed from Master's Program in Physical Education, Graduate School ... (with English subtitles)|University of Tsukuba. 筑波 ...
  14. [14]
    Masato Yoshii Trades and Transactions - Baseball Almanac
    The Baseball Almanac trades and transactions database includes Rule 5 Draft picks, free agency information, voided trades, waiver picks, expansion draft ...Missing: 1983 Hankyu
  15. [15]
  16. [16]
    Masato Yoshii Player Card | Baseball Prospectus
    Masato Yoshii. P. Team logo. WAS. Age: 60. Birth Date: 1965 Apr 20. Birthplace: Osaka, Japan. Height: 6' 2". Weight: 215 lb. B/T: Right/Right ...
  17. [17]
    Expos release Masato Yoshii | CBC Sports
    Dec 4, 2002 · The Montreal Expos put pitcher Masato Yoshii on waivers on Tuesday in order to give him his unconditional release.Missing: date | Show results with:date
  18. [18]
    METS WANT HIDEO TO FEEL AT HOME - New York Daily News
    Jun 10, 1998 · Like his Japanese compatriot and fellow pitcher, Yoshii might not speak much English, but there are some things that need no translation. The ...Missing: MLB | Show results with:MLB
  19. [19]
    Memories of Masato Yoshii - Ultimate Mets Database
    He is currently the manager of the Chiba Lotte Marines in Japan, after coaching for them—and multiple other teams—for a few years. Meet the ...
  20. [20]
    BlueWave to sign Yoshii to one-year deal - The Japan Times
    Jan 8, 2003. The Orix BlueWave of the Pacific League and former Montreal Expos pitcher Masato Yoshii agreed to a one-year deal Tuesday, sealing Yoshii's ...
  21. [21]
    Buffaloes happy with their end of Yoshii-to-Marines deal
    Jul 6, 2007 · On June 28 the Orix Buffaloes traded popular pitcher Masato Yoshii to the Chiba Lotte Marines for infielder Koji Hirashita. Thursday night, a ...Missing: 2005-2007 | Show results with:2005-2007
  22. [22]
    Yoshii tries to mix and match MLB and NPB styles as pitching coach ...
    Feb 28, 2008 · Yoshii pitched 19 seasons at the top level in Japan and North America, five of them in MLB for the Mets, Rockies, and Expos.Missing: history | Show results with:history
  23. [23]
    Sasaki's perfect game backed by science-based training methods
    Apr 12, 2022 · After retiring from professional baseball, Yoshii studied baseball coaching theory at the Tsukuba University graduate school. His coaching ...
  24. [24]
    [JAPAN SPORTS NOTEBOOK] Shohei Ohtani Sets New Benchmark ...
    Oct 9, 2022 · Yoshii to Lead Marines in 2023. Masato Yoshii is the Chiba Lotte Marines' new manager, the Pacific League club revealed on Friday, October 7.
  25. [25]
    The Story So Far: Chiba Lotte Marines, 2025 Season (Through May)
    Jun 8, 2025 · Under manager Masato Yoshii, they had made the playoffs in the previous two seasons and 2025 was to be the culmination of the “Vision 2025 ...
  26. [26]
    New York Mets At the plate and on the base paths, Rickey ...
    Oct 18, 1999 · Has a big slow curve that, if flat, is hittable. Changeup looks almost like a screwball. Great glove. Masato Yoshii, RHP Best pitch is a split- ...
  27. [27]
    CHANGE OF PACE IS MORE YOSHII'S SPEED
    Apr 18, 1998 · But I expected him to throw a lot of strikes and be in a lot of good counts. “Throw quality pitches, throw a lot of strikes and have no fear of ...Missing: efficiency | Show results with:efficiency
  28. [28]
    Hoping to Become the Next Hot Baseball Export From Japan
    Feb 29, 2008 · Masato Yoshii is the first Japanese player who played in the major leagues to return to Japan and coach. Might it follow that we'll be soon ...
  29. [29]
  30. [30]
    吉井 理人(千葉ロッテマリーンズ) | 個人年度別成績 - NPB
    ... 終了時. 吉井 理人; よしい・まさと. 投打, 右投右打. 身長/体重, 188cm/95kg. 生年月日, 1965年4月20日. 経歴, 箕島高. ドラフト, 1983年ドラフト2位. 投手成績; 打撃成績 ...
  31. [31]
    Hoping to become Japan's next hot baseball export
    Dec 9, 2008 · 81 is the eighth uniform number of Masato Yoshii's professional career. ... He signed with the Orix Blue Wave and pitched six more seasons ...<|control11|><|separator|>
  32. [32]
    Ex-teammates, foes praise hurler Nomo for impact - The Japan Times
    Jul 20, 2008 · Nomo announced his retirement on Thursday, bringing an end to an illustrious Major League Baseball career that began in 1995. Nomo's 123 wins ...Missing: 2007 | Show results with:2007