From Newark, Delaware, Grinnage earned 1st-team All-State as a Tight End and Defensive End. He was rated the #21 TE in the nation, and the #2 best player in the state of Delaware by Rivals.com. He committed to play collegiately at NC State.
As a sophomore, Grinnage was named to the midseason list for the Mackey Award, and tied for the team lead in TD receptions. A 3-year letterman at NC State, Grinnage finished his college career with 67 receptions for 798 yards and 9 touchdowns. He declared for the NFL following his red-shirt junior season.
Grinnage, 6’5″, 265 lbs, signed as a rookie free agent with the Green Bay Packers, but was released following an injury during minicamp. Healthy, he joined The Spring League to gain more NFL exposure and playing time against elite competition.
His performance at The Spring League garnered NFL attention, leading to a contract with the Jacksonville Jaguars on their active roster.