Sullivan was selected by the
Colorado Rockies in the second round with the 46th pick in the
2023 Major League Baseball draft. He signed with the Rockies for $1,700,000. Sullivan made his professional debut after signing with the
Arizona Complex League Rockies and also played one game with the
Fresno Grizzlies, pitching four scoreless innings between the two teams. He split the 2024 season between the
Spokane Indians and
Hartford Yard Goats, going 9-2 with a 2.11 ERA and 125 strikeouts over innings. Sullivan opened the 2025 season on rehab assignments with the ACL Rockies and Fresno before being assigned to Hartford. ==References==