Hillman begins his first season with the Ducks and ninth in professional baseball. The pitcher was acquired by the Ducks from the Cleburne Railroaders of the American Association in exchange for a player to be named later. The southpaw made two starts with Cleburne in 2024, allowing just three runs (one earned) in 10.2 innings of work while striking out five batters. His contract was then purchased by the Colorado Rockies organization on May 20, and he went on to make 19 appearances (nine starts) with Triple-A Albuquerque.

The 27-year-old began his career by pitching for six seasons in the Cleveland Indians organization (2015-19, 2021), peaking at Triple-A. He was named an Eastern League Mid-Season All-Star in 2021 with Double-A Akron, a Carolina League Mid-Season All-Star in 2019 with High-A Lynchburg, and a New York-Penn League All-Star in 2016 with Low-A Mahoning Valley. The Florida native also pitched with the Lake Country DockHounds of the American Association in 2023, making nine appearances (eight starts). Hillman was originally selected by the Indians in the second round of the 2015 amateur draft from Olympia High School (Orlando, Fla.).