Koonce was a member of the Buffalo Bulls for four seasons. He served primarily as a backup for his first two seasons.[3] Koonce was named first-team All-Mid-American Conference (MAC) after recording 34 tackles, 11 tackles for loss and nine sacks in his junior season.[4] He was named the Defensive MVP of the 2019 Bahamas Bowl after a two sack performance against the Charlotte 49ers.[5] Koonce repeated as a first-team All-MAC selection as a senior after recording 30 tackles, 6.5 tackles for loss, and five sacks after playing in six games due to the MAC's COVID-19-shortened 2020 season.[6][7] He became only the fourth UB player to be invited to play in the Senior Bowl.[1]
Koonce was selected in the third round with the 79th overall pick of the 2021 NFL draft by the Las Vegas Raiders.[10] The Raiders had received the 79th pick used to select Koonce in a trade that sent Rodney Hudson to the Arizona Cardinals.[11] On July 23, 2021, Koonce signed his four-year rookie contract with Las Vegas.[12]
Koonce was activated for Week 2 against the Pittsburgh Steelers but did not appear in the game. He was next activated before Week 13 following an injury to linebacker Carl Nassib.[13] Koonce made his NFL debut on December 5 and, despite taking the field for only seven plays on defense and four on special teams, recorded a sack of WashingtonquarterbackTaylor Heinicke.[14][15]
2023
Koonce had a break out year in 2023, playing opposite Maxx Crosby on the Raiders defensive line. By Week 14 against Minnesota Vikings, Koonce had roughly doubled his playing time under interim head coach Antonio Pierce. Koonce had more quarterback hits in Weeks 14-16 than he had the rest of the season combined.[16]
Kooncce had his best statistical game as a pro in a Christmas Day matchup against their division rival Kansas City Chiefs. The Raiders needed a win to keep their playoff hopes alive. Koonce harassed Chiefs quarterback Patrick Mahomes all game, finishing with career highs in pressures (8) and sacks (3).[17]
2024
Koonce was placed on injured reserve on September 7, 2024 after suffering a knee injury in practice.[18] On September 20, it was announced that the injury would end Koonce's season.[19]