Isaac Mattson

Isaac Gerald Mattson (born July 14, 1995) is an American professional baseball pitcher in the Pittsburgh Pirates organization. He has previously played in Major League Baseball (MLB) for the Baltimore Orioles.

Amateur career
Mattson attended Harbor Creek High School in Harborcreek, Pennsylvania, where he played both baseball and basketball. In 2014, his senior year, he went 6–0 with a 0.67 ERA along with batting .531. He was not drafted out of high school in the 2014 Major League Baseball draft and enrolled at the University of Pittsburgh where he played college baseball.

In 2015, as a freshman at Pitt, Mattson appeared in 22 games, going 1–1 with a 3.82 ERA, and in 2016, his sophomore season, he pitched 34 innings in relief, compiling a 2–0 record with a 3.71 ERA. After his sophomore year, he played for the Chatham Anglers of the Cape Cod Baseball League and was named an all-star. In 2017, as a junior, he pitched 31 innings out of the bullpen, going 1–0 with a 2.87 ERA, striking out 41.

Los Angeles Angels
After the season, Mattson was drafted by the Los Angeles Angels in the 19th round of the 2017 Major League Baseball draft.

After signing, Mattson made his professional debut with the Arizona League Angels before being promoted to the Orem Owlz, where he was named an All-Star. In $31 1⁄3$ innings between the two clubs, he went 1–0 with a 1.44 ERA. In 2018, he played for the Burlington Bees and the Inland Empire 66ers, going 7–4 with a 3.82 ERA in 25 games (11 starts), and in 2019, he began the year with the 66ers before being promoted to the Mobile BayBears in May. In August, he was promoted to the Salt Lake Bees. Over 37 relief appearances between the three clubs, Mattson pitched to a 6–3 record with a 2.33 ERA, striking out 110 over $73 1⁄3$ innings. He was selected to play in the Arizona Fall League for the Mesa Solar Sox following the season.

Baltimore Orioles
On December 4, 2019, Mattson (alongside Zach Peek, Kyle Bradish, and Kyle Brnovich) was traded to the Baltimore Orioles in exchange for Dylan Bundy. He did not play a minor league game in 2020 due to the cancellation of the minor league season caused by the COVID-19 pandemic.

On November 20, 2020, Mattson was added to the 40-man roster. On May 3, 2021, Mattson was promoted to the major leagues for the first time. Mattson made his major league debut on May 7, pitching 2/3 of an inning and allowing one run on a Marwin González RBI double. He was optioned to the Triple-A Norfolk Tides the following day. On June 30, Mattson was recalled by the Orioles. He recorded his first career strikeout on July 3, striking out Los Angeles Angels infielder David Fletcher. Over 4 appearances for the Orioles in 2021, Matson posted a 6.23 ERA with 3 strikeouts.

On April 8, 2022, Mattson was outrighted to Triple-A Norfolk. On July 18, the Orioles released Mattson from the organization.

Washington Wild Things
On August 6, 2022, Mattson signed with the Washington Wild Things of the Frontier League. He made 12 appearances for Washington, recording a 2.40 ERA with 23 strikeouts in 15.0 innings pitched. On December 5, Mattson was released by the Wild Things after having his contract option declined.

Southern Maryland Blue Crabs
On March 31, 2023, Mattson signed with the Southern Maryland Blue Crabs of the Atlantic League of Professional Baseball. In 18 appearances for the Blue Crabs, Mattson logged a 3.32 ERA with 24 strikeouts and 3 saves in 19.0 innings pitched.

Minnesota Twins
On June 22, 2023, Mattson signed a minor league contract with the Minnesota Twins organization. In 21 appearances for the Double–A Wichita Wind Surge, he registered a 3.62 ERA with 42 strikeouts across $32 1⁄3$ innings of work. Mattson elected free agency following the season on November 6.

Pittsburgh Pirates
On December 11, 2023, Mattson signed a minor league contract with the Pittsburgh Pirates.