Hagan spent five seasons at the University of Texas at Arlington, where he made 68 appearances for the Mavericks. During his redshirt senior season, he made 20 appearances on the mound.

A 2020 graduate of McKinney Boyd High School, Hagan was a standout prep pitcher, posting a 1.20 ERA while earning First Team All-State honors and being named a DFW Top 10 pitcher. In 2025, he pitched in the MLB Draft League with the State College Spikes, appearing in 17 games and posting a 2.08 ERA.