Cleveland Indians The
Cleveland Indians selected Mathias in the third round of the
2015 Major League Baseball draft. Mathias played for the
Mahoning Valley Scrappers in 2015, hitting .282/.382/.408 with two
home runs and 32
runs batted in (RBIs). He split the 2016 season between the
Lynchburg Hillcats and the
Akron RubberDucks, hitting a combined .267/.351/.396 with five home runs and 61 RBIs. In the Carolina League, he was 8th in runs (70), 3rd in doubles (39), and 7th in hit by pitch (10). He was named a Carolina League post-season All Star, and an MiLB organization All Star. Mathias spent the 2017 and 2018 seasons in Akron, hitting .212 in 35 games in 2017, and .232 with eight home runs and 45 RBIs in 2018. He was named an MiLB organization 2018 All Star.
Milwaukee Brewers Cleveland traded Mathias to the
Milwaukee Brewers in exchange for Andres Melendez on November 20, 2019, and the Brewers added him to their
40-man roster. Mathias made his MLB debut on August 4, 2020, as a pinch runner. In 2020 with the Brewers he batted .278/.278/.361 in 36 at bats, playing primarily right field. On March 16, 2021, Mathias was placed on the 60-day injured list due to a torn
labrum in his shoulder, and remained there through the end of the season. On November 19, 2021, Mathias was outrighted off of the 40-man roster and sent to the Triple-A
Nashville Sounds. On May 24, 2022, the Brewers selected Mathias' contract from Triple-A Nashville. In 2022 with Nashville, he batted .318/.421/.518 in 170 at bats. For the season with the Brewers, he batted 2–16, playing six games at second base.
Texas Rangers On August 1, 2022, Mathias and pitcher
Antoine Kelly were traded to the
Texas Rangers in exchange for pitcher
Matt Bush. With Round Rock he batted .345/.429/.517 in 29 at bats, playing primarily second base. On March 4, 2023, Mathias was designated for assignment by the Rangers after the signing of
Will Smith was made official.
Pittsburgh Pirates On March 8, 2023, Mathias was traded to the
Pittsburgh Pirates in exchange for Ricky DeVito. Mathias was optioned to the Triple-A
Indianapolis Indians to begin the 2023 season, and with them he batted .273/.393/.384 in 99 at bats, playing primarily right field and second base. In 22 games for Pittsburgh, Mathias batted .231/.355/.269 in 52 at bats with no home runs, 4 RBIs, and 3 stolen bases without being caught. He played 15 games at second base, and two games in right field. On June 25, he was
designated for assignment by the Pirates.
Seattle Mariners On July 2, 2023, Mathias was claimed off waivers by the
Seattle Mariners. With the Triple–A
Tacoma Rainiers, he batted .345/.427/.500 in 58 at bats, playing primarily second base. After 5 games with San Francisco, Mathias was placed on the injured list with a right shoulder strain on August 18. He was transferred to the 60–day injured list on August 22, ending his season. Following the season on November 1, Mathias was removed from the 40–man roster and sent outright to the Triple–A
Sacramento River Cats. However, Mathias rejected the assignment and elected free agency on November 3.
Cincinnati Reds On November 29, 2023, Mathias signed a minor league contract with the
Cincinnati Reds. However, he did not appear in a game for the organization and elected free agency following the season on November 4, 2024.
Long Island Ducks On April 4, 2025, Mathias signed with the
Long Island Ducks of the
Atlantic League of Professional Baseball. In 2 games he went 1 for 6 (.167). ==Personal life==