When the Kansas City Royals made the trade to acquire Jesse Hahn and Heath Fillmyer in the 2017 offseason, the hope was that he was going to be in the rotation for the team. In 2017, Hahn made 13 starts (14 appearances) for the Athletics while tossing 69.2 innings with 55 strikeouts and 27 walks to the tune of a 5.30 ERA.
However, that plan was quickly shutdown (literally) when Hahn started feeling soreness in his elbow during spring training. Eventually, he was formally shut down and after numerous occurrences of being close to returning and being shut down again.