On May 7, 2015, Fiers became the 73rd pitcher in MLB history to record an Immaculate inning when he struck out Enrique Hernandez, Carlos Frias, and Joc Pederson on 9 consecutive pitches in the fourth inning. In 21 starts, Fiers was 5–9 with an ERA of 3.89. In 118 innings, he struck out 121.
