Sweeney provided depth to Yakima Valley’s pitching staff in 2021 before heading to Washington for his freshman year. He had nine relief appearances in the regular season for the Pippins, going 0-2 with a save and a 5.82 ERA in 17 innings. Sweeney also appeared in two playoff games, striking out a pair over 1.2 innings without allowing a run. He was ranked No. 24 Top Prospect by Baseball Northwest in the Class of 2021.