Mark Leiter Jr. Bio
Mark Edward Leiter Jr. is an American professional baseball pitcher who most recently played in Major League Baseball for the New York Yankees before signing with the Athletics. Across his MLB career he has also appeared for the Philadelphia Phillies, Toronto Blue Jays, and Chicago Cubs. A right-handed reliever, he has spent the majority of his professional career working out of the bullpen after beginning as a starting pitcher in the minor leagues.
Born on March 13, 1991, Leiter comes from one of baseball’s most recognizable families, with both his father and uncle having pitched in the major leagues. After playing college baseball at the New Jersey Institute of Technology, he was selected by the Phillies in the 22nd round of the 2013 MLB draft and reached the majors in 2017.
Early Life and Background
Mark Edward Leiter Jr. grew up in New Jersey and attended Toms River High School North in Toms River, where he played baseball before moving on to the college ranks. His path into professional baseball was shaped in part by his family name, as his father, Mark Leiter, and his uncle, Al Leiter, both pitched in the major leagues.
Following high school, Leiter played college baseball at the New Jersey Institute of Technology, a program that allowed him to continue developing as a pitcher while staying close to home. His performance at NJIT drew enough attention from professional scouts to lead to his selection in the 2013 MLB draft.
Path to Professional Baseball
Leiter was drafted by the Philadelphia Phillies in the 22nd round of the 2013 Major League Baseball draft and signed with the organization that summer. He made his professional debut that year with the GCL Phillies and was promoted during the season to the Clearwater Threshers and the Lakewood BlueClaws. Across 45 innings pitched between the three affiliates, he posted a 4–0 record with a 1.20 ERA, an impressive start to his minor league career.
Over the next three seasons, Leiter progressed through the Phillies’ system, splitting time as both a starter and a reliever. In 2014 he pitched for Lakewood and Clearwater, going 9–12 with a 4.35 ERA across 27 starts, and in 2015 he appeared for Clearwater and the Reading Fighting Phils, posting an 8–7 record and a 3.09 ERA in 27 games. He spent the 2016 season with Reading, where he recorded a 6–3 mark and a 3.39 ERA in 23 appearances, including 17 starts.
Mark Leiter Jr. Career
Early Career (2013–2017)
After beginning the 2017 season with the Lehigh Valley IronPigs, Leiter received his first major league call-up on April 18, 2017, and made his MLB debut on April 28 with the Philadelphia Phillies. His rookie year was a learning experience, as he finished with a 3–6 record and a 4.96 ERA while recording 84 strikeouts across 27 appearances, 11 of which were starts.
Leiter opened 2018 on the disabled list and was optioned to Lehigh Valley after being activated. On September 1, 2018, he was claimed off waivers by the Toronto Blue Jays. After being activated, he made eight appearances for Toronto but struggled to a 13.50 ERA in limited work, and was designated for assignment on November 26. He later cleared waivers and was assigned to the Triple-A Buffalo Bisons.
Recovery and Independent Ball (2019–2021)
On March 17, 2019, the Blue Jays announced that Leiter would miss the entire 2019 season after undergoing Tommy John surgery. He elected free agency following the season on November 4. Looking for a fresh opportunity, Leiter signed a minor league contract with the Arizona Diamondbacks on February 13, 2020, but did not appear in a game that year after the minor league season was canceled because of the COVID-19 pandemic. He was released by the Diamondbacks organization on May 22.
On July 9, 2020, Leiter signed with the Somerset Patriots of the Atlantic League of Professional Baseball. He did not play in a scheduled game for the Patriots after the 2020 ALPB season was canceled due to the pandemic, though he later took part in the pop-up SOMERSET Professional Baseball Series the club organized. In 2021, he signed a minor league deal with the Detroit Tigers and split the year between the Double-A Erie SeaWolves and the Triple-A Toledo Mud Hens, going 10–8 with a 3.77 ERA and 145 strikeouts in 25 appearances before becoming a free agent again.
Chicago Cubs Era (2022–2024)
On December 17, 2021, Leiter signed a minor league contract with the Chicago Cubs, and on April 16, 2022, his contract was selected and he joined the major league roster. He made an immediate impact in relief, recording his first career save on August 16 against the Washington Nationals. In 35 appearances for Chicago in 2022, Leiter registered a 2–7 record and a 3.99 ERA with 73 strikeouts in 67 2/3 innings pitched.
The Cubs designated Leiter for assignment on January 13, 2023, after the signing of Eric Hosmer became official. He cleared waivers and was outrighted to the Triple-A Iowa Cubs on January 19, but rejected the outright assignment four days later and elected free agency. He re-signed with the Cubs on a minor league deal on February 2 and had his contract selected on March 30. In 69 relief appearances during the 2023 season, he logged a 3.50 ERA with 77 strikeouts and four saves across 64 1/3 innings. Leiter made 39 appearances out of the bullpen for the Cubs in 2024, compiling a 2–4 record and a 4.21 ERA with 53 strikeouts over 36 1/3 innings pitched before being traded.
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 for New York, posting a 2–1 record and a 4.98 ERA with 33 strikeouts across 21 2/3 innings pitched.
Leiter returned to the Yankees bullpen in 2025, appearing in 59 games and compiling a 6–7 record and a 4.84 ERA with 54 strikeouts and two saves across 48 1/3 innings pitched. On November 21, 2025, he was non-tendered by New York and became a free agent.
Athletics Era (2025–Present)
On December 17, 2025, Leiter signed a one-year, $2.85 million contract with the Athletics, returning to a major league roster. The deal positioned him as a veteran presence in the Oakland bullpen for the upcoming season.
Driving Style and Strengths
As a converted starter, Leiter relies on the durability and pitch mix he developed in the minor leagues to handle multi-inning relief appearances. His strikeout totals at the Triple-A level, including 145 in 2021, suggest an ability to miss bats when he is commanding his stuff.
Notable Events and Milestones
Leiter’s first career save came on August 16, 2022, against the Washington Nationals, marking a turning point in his transition to a full-time relief role. His family’s deep baseball roots, including his father Mark Leiter, his uncle Al Leiter, and his cousin Jack Leiter of the Texas Rangers, place him among the more prominent pitching families in recent MLB history.
Mark Leiter Jr. Family
Family Background and Baseball Lineage
Mark Leiter Jr. was raised in a family steeped in professional pitching. His father, Mark Leiter, and his uncle, Al Leiter, both pitched in the major leagues, giving him an early understanding of life in professional baseball. His cousin, Jack Leiter, is a pitcher for the Texas Rangers, continuing the family’s presence in MLB.
Personal Life
Leiter has been a resident of the Lanoka Harbor section of Lacey Township, New Jersey. His long-standing ties to the Garden State have remained a constant throughout a career that has taken him through organizations in multiple cities.
2025 Season Performance
Leiter opened the 2025 season in the New York Yankees bullpen following his July 2024 trade from Chicago. Over 59 appearances, he posted a 6–7 record with a 4.84 ERA, 54 strikeouts, and two saves across 48 1/3 innings, providing middle and late relief for a contending club.
Despite flashes of effectiveness, his overall numbers reflected the volatility of a long relief role. On November 21, 2025, New York non-tendered Leiter, making him a free agent, and on December 17, 2025, he signed a one-year, $2.85 million contract with the Athletics to provide veteran depth in their bullpen for the coming season.
Heading into the next campaign, Leiter is expected to serve as a reliable multi-inning option for Oakland, with the opportunity to re-establish himself as a consistent late-inning arm after several seasons of shuttling between rosters and affiliates.