Mark Leiter Jr. Bio
Mark Edward Leiter Jr. (born March 13, 1991) is an American professional baseball player and pitcher for the Oakland Athletics of Major League Baseball. Leiter Jr. broke into organized baseball after starring at the New Jersey Institute of Technology and was selected by the Philadelphia Phillies in the 22nd round of the 2013 MLB draft. He made his major league debut in 2017 and has since worked primarily as a right-handed bullpen pitcher for multiple clubs.
Early Life and Background
Mark Edward Leiter Jr. grew up in New Jersey and attended Toms River High School North in Toms River, New Jersey. He continued his education and baseball development at the New Jersey Institute of Technology, where his collegiate work drew attention from professional scouts and led to his selection in the 2013 Major League Baseball draft.
Leiter Jr. is part of a noted pitching family. His father, Mark Leiter, and his uncle, Al Leiter, both pitched in Major League Baseball. That family connection provided early exposure to the professional game and practical guidance during Leiter Jr.’s formative baseball years. He has been a resident of the Lanoka Harbor section of Lacey Township, New Jersey.
Path to Baseball
Leiter Jr. advanced through the Phillies’ minor league system after signing in 2013, beginning his professional career with the Gulf Coast League Phillies and receiving promotions to the Clearwater Threshers and Lakewood BlueClaws that same season. In his first professional season he combined for 45 innings with a 4–0 record and a 1.20 ERA across the three stops.
He spent the following seasons working as both a starter and a reliever in the Phillies organization, pitching for Lakewood, Clearwater and Reading. Leiter posted steady numbers in the high minors across 2014–2016 and arrived at Triple–A Lehigh Valley to begin 2017, positioning himself for his major league call-up later that spring.
Mark Leiter Jr. Career
Early Career (2013–2016)
After being drafted by the Philadelphia Phillies in the 22nd round of the 2013 draft, Leiter Jr. signed and made immediate progress through the system. He combined for strong results in 2013, then followed with a full slate of starts and relief appearances in 2014 and 2015. In 2015 he posted an 8–7 record with a 3.09 ERA in 27 games, including 21 starts, while splitting time between Clearwater and Reading.
Leiter spent the 2016 season with the Reading Fighting Phils, where he went 6–3 with a 3.39 ERA in 23 games, 17 of them starts. Those performances earned him a place at Triple–A Lehigh Valley to begin 2017 and set the stage for his major league debut that season.
Philadelphia Phillies Breakthrough (2017–2018)
Leiter Jr. received his first major league call-up in April 2017 and made his MLB debut later that month. He finished his rookie season with 27 appearances, including 11 starts, compiling a 3–6 record, a 4.96 ERA and 84 strikeouts. The 2017 campaign represented his initial transition from a minor-league starter to a major-league pitcher used in multiple roles.
Leiter began 2018 on the disabled list and spent time with the Lehigh Valley IronPigs after activation. His early big-league tenure included movement between starter and reliever roles as the Phillies evaluated his best long-term fit at the major league level.
Toronto Blue Jays and Tommy John Recovery (2018–2020)
Leiter Jr. was claimed off waivers by the Toronto Blue Jays on September 1, 2018, and made eight appearances for Toronto that month. He struggled in that brief stint and was designated for assignment in November before remaining in the Blue Jays organization at Triple–A. In March 2019 the Blue Jays announced Leiter would miss the entire 2019 season after undergoing Tommy John surgery.
Following surgery and recovery, Leiter signed a minor league contract with the Arizona Diamondbacks in February 2020 but did not appear in games that year because the minor league season was canceled. He later signed with independent and other organizations as he worked his way back to affiliated baseball.
Return and Minor League Work (2020–2021)
In July 2020 Leiter signed with the Somerset Patriots of the Atlantic League, though the Atlantic League season circumstances limited competitive appearances. Leiter returned to affiliated ball with a minor league contract with the Detroit Tigers organization in March 2021. He split the 2021 season between Double–A Erie and Triple–A Toledo, making 25 appearances, posting a 10–8 record with a 3.77 ERA and compiling a high strikeout total as he re-established himself as a professional pitcher.
Chicago Cubs Era (2022–2024)
Leiter signed a minor league contract with the Chicago Cubs in December 2021 and had his contract selected by the major league club in April 2022. He recorded his first career save on August 16, 2022, in a game against the Washington Nationals. In 2022 he made 35 appearances for Chicago and registered a 2–7 record with a 3.99 ERA and 73 strikeouts across 67 2/3 innings.
Leiter returned to the Cubs for 2023 and 2024, including a full major league roster role in 2023 when he logged 69 relief appearances with a 3.50 ERA, 77 strikeouts and four saves over 64 1/3 innings. In 2024 he made 39 appearances for the Cubs, compiling a 2–4 record and 4.21 ERA with 53 strikeouts in 36 1/3 innings.
New York Yankees Era (2024–2025)
On July 30, 2024, the Cubs traded Leiter Jr. to the New York Yankees in exchange for infielder Ben Cowles and pitcher Jack Neely. He made 21 appearances down the stretch in 2024 for the Yankees, posting a 2–1 record and a 4.98 ERA with 33 strikeouts across 21 2/3 innings. Leiter remained with New York for the 2025 season and appeared in 59 games out of the bullpen, compiling a 6–7 record, a 4.84 ERA, 54 strikeouts and two saves across 48 1/3 innings.
Following the 2025 season the Yankees non-tendered Leiter on November 21, 2025, making him a free agent ahead of the 2026 season.
Athletics Era (2026–Present)
On December 17, 2025, Mark Edward Leiter Jr. signed a one-year contract with the Oakland Athletics worth $2.85 million. The agreement brought Leiter to the Athletics’ bullpen for the 2026 season, continuing his role as a veteran relief pitcher in Major League Baseball.
Driving Style and Strengths
Leiter Jr. has established himself primarily as a bullpen pitcher at the major league level, bringing swing-and-miss stuff and the ability to work multiple innings out of the pen. His career includes relief saves and high strikeout totals in seasons where he worked regularly, reflecting his value as a late-inning and multi-inning option for club bullpens.
Notable Events and Milestones
Key moments in Leiter Jr.’s career include his major league debut in April 2017, his first career save on August 16, 2022, and returning to the majors following Tommy John surgery. His family ties to longtime major leaguers Mark Leiter and Al Leiter, and his cousin Jack Leiter’s professional pitching career, remain notable elements of his baseball biography.
Mark Leiter Jr. Career Wins
As of June 8, 2026, Mark Edward Leiter Jr. holds a major league win–loss record of 16–30 with a career earned run average of 4.64 and 426 strikeouts. Those totals reflect his contributions across multiple teams and roles since his debut in 2017.
Major League Baseball Highlights
Leiter Jr.’s MLB highlights include his 2017 rookie season with the Philadelphia Phillies, a multi-inning relief role with the Chicago Cubs that yielded career-high appearance totals, his midseason trade to the New York Yankees in 2024, and a full-season bullpen role in 2025. His first career save and seasons with high strikeout totals stand out among his major league achievements.
Other Wins & Perfromances
In the minor leagues and early professional years, Leiter Jr. posted strong results that helped advance his career, including a dominant handful of innings in 2013 and consistent work at Reading and Lehigh Valley. His performances in Triple–A and Double–A in 2021 helped him return to the major leagues after surgery and organizational moves.
Mark Leiter Jr. Family
Family Background and Racing Lineage
Leiter Jr. comes from a family with deep major league pitching roots. His father, Mark Leiter, and his uncle, Al Leiter, both pitched in Major League Baseball. His cousin, Jack Leiter, is also a professional pitcher currently with the Texas Rangers organization. That family background has been a recurring theme throughout his baseball career.
Personal Life
Leiter Jr. has maintained residency in the Lanoka Harbor section of Lacey Township, New Jersey. Public accounts note his ties to the local community and his continued connection to New Jersey, where he attended high school and college before turning professional.
2025 Season Performance
During the 2025 season, Mark Edward Leiter Jr. appeared in 59 games for the New York Yankees, recording a 6–7 record with a 4.84 ERA, 54 strikeouts and two saves across 48 1/3 innings. He served as a regular bullpen option and logged significant innings in relief roles throughout the year.
Following the conclusion of the 2025 campaign, the Yankees non-tendered Leiter on November 21, 2025, and he entered free agency. On December 17, 2025, he signed a one-year, $2.85 million contract with the Oakland Athletics, setting the stage for his 2026 season with a new club.