In 2012 Giller became a pillar of the Oral Roberts rotation, making 14 starts and recording a 6-4 record with a 3.42 ERA. He spent his first season of collegiate eligibility as a Nebraska Cornhusker in 2010, suffering a season-ending elbow injury that required surgery. After deciding to transfer in 2011 to Oral Roberts, Giller redshirted. In his debut season in 2012 with the Golden Eagles, Giller was stellar while establishing himself as a workable starter in the team’s rotation. He was named a Louisville Slugger First-Team All-American his senior year of high school in 2009, and was drafted out of high school that same year in the 21st round of the MLB amateur draft by the Toronto Blue Jays