Allsup attended Dothan High School in Alabama. He posted a 9-1 record and 1.73 ERA as a senior, and struck out 107 batters. He was ranked the 4th overall prospect and the no. 1 RHP in the state of Alabama. He chose to join Auburn following his high school career.
As a freshman, Allsup threw out of the bullpen for Auburn, making 23 appearances on the year. He had a 3.38 ERA with 36 K's and 17 walks in 29.1 innings pitched. He recorded 2 saves out of the pen as well.
Last season as a sophomore, Allsup made 20 appearances including 8 starts. He posted a 1-2 record and a 5.47 ERA. He struck out 49 batters and walked 33 in 49.1 innings. he also recorded 2 more saves out of the pen for the Tigers.
This year is Allsup's junior season. He expects to take over a rotation spot for Auburn and lower his ERA from last year in order to climb back up draft boards ahead of this year's draft.