Miller recorded 35 strikeouts in his first 33 innings of work in the 2017 season with his best outing a 7-inning 5-2 win over Northwestern where he struck out 12 and allowed two runs on four hits. At Wenatchee High School, Miller also lettered in football and was named First Team All-League in basketball. He was a two-time All-State First Team pick and a four-year letter winner in baseball. He was named the 2015 and 2016 Columbia Basin Big 9 Conference Pitcher of the Year and was a two-time all-league selection as a first baseman. He led the league in ERA (0.52) and strikeouts (98) as a senior.