Kelly begins his first season with the Ducks, third in the Atlantic League and ninth in professional baseball. The right-hander spent the past two seasons (2024-25) with the Hagerstown Flying Boxcars, going 7-9 with a 4.02 ERA and 18 saves in 111 games, striking out 116 across 123.0 innings pitched. 

The 29-year-old was signed by the Oakland Athletics as an international free agent from the Dominican Republic in 2017. He spent five seasons (2017-19, 2021-22) in the Athletics organization, recording a record of 16-16 with 3.64 ERA and one save in 57 games and 38 game starts, striking out 228 in 247.1 innings of work.