Creasy earned a spring training invite after participating in the Ducks open player tryout on April 14. He spent the first six seasons of his career in the Pittsburgh Pirates organization, reaching as high as Triple-A in 2016. The North Carolina native collected Eastern League Mid-Season All-Star honors with Double-A Altoona in 2015 and was 12-8 with a 4.41 ERA, one complete game, one save and 147 innings pitched over 27 games (25 starts). The 25-year-old pitched with the St. Paul Saints of the American Association in 2017, making 11 starts and striking out 49 batters in 57 innings. Creasy was originally drafted by the Pirates in the eighth round of the 2011 amateur draft.