Head coach Scott Satterfield told ESPN Radio on Wednesday that the quarterback left the program, according to WDRB's Eric Crawford.
"Luke came in last week and decided that this wasn't the place for him," Satterfield said via The Athletic. "He wanted to come in and be a starting quarterback."
The redshirt freshman, younger brother of Carolina Panthers star Christian McCaffrey, didn't participate in spring practices and had only been on campus for a short time before deciding to leave the Cardinals, per The Athletic's Mitch Sherman.
McCaffrey transferred to Louisville from Nebraska in February after spending his first two years of college in Lincoln. He made two starts in 2020 and appeared in five of the Cornhuskers' other six games.
The young passer was initially attempting to compete with incumbent starter Malik Cunningham at Louisville. Cunningham was inconsistent last season but has shown promise as a dual-threat weapon.