This offseason, the Detroit Lions lost defensive coordinator Aaron Glenn, who took the head coaching job with the New York Jets. The Lions promoted linebackers coach Kelvin Sheppard to the defensive coordinator role for the 2025 NFL season.

Despite dealing with numerous injuries to their defense, the Lions finished seventh in points allowed and 20th in yards allowed out of the NFL’s 32 teams in 2024.

Five of Detroit’s starting defenders for the season opener were absent for the Lions’ playoff finale, with defensive end Aidan Hutchinson, defensive tackle Kyle Peko, and linebacker Derrick Barnes missing at least 12 games each.

However, Sheppard highlighted the valuable experience the young Detroit defense gained as he gets ready for his first season as a coordinator.

“We have a young core, a young nucleus,” Sheppard remarked. “But one player that stands out to me is Terrion Arnold. There’s so much untapped potential there that he doesn’t even realize.

“He called me a couple of days ago just joking around. I asked, ‘Where are you at?’ He said, ‘Down in Florida.’ I told him, ‘You better enjoy it now, because when you come back, we’re getting to work, brother.’ And he said, ‘Oh, absolutely, Coach! I know how you are!’”

Arnold, who came to Detroit from Alabama as the 24th pick in the 2024 NFL Draft, missed one game but was one of five rookies to play at least 900 defensive snaps during the 2024 regular season. He played all 75 snaps in the Lions’ 45-31 loss to the Washington Commanders in the second round of the NFC playoffs on January 18.

Arnold struggled in the first four games of the season, committing five defensive pass interference penalties, two defensive holding penalties, and one face mask penalty. In his remaining 13 games, he was penalized just three times, and with Carlton Davis out due to a broken jaw, Arnold played the most cornerback snaps for the Lions this season.

“He has the right mindset,” Detroit general manager Brad Holmes said at the NFL Scouting Combine. “He took some early hits, with some aggressive penalties early on. But like I said at the end of the season, I felt he settled down after a while.

“He’s a very coachable player. He cares, he’s passionate, he’s proud, so he’ll do what’s necessary. He wants to be great, and we want him to be great, so I’m confident he’ll continue to grow.”

Holmes also praised former Alabama standout Deshea Townsend for his role in Arnold’s development as the Lions’ secondary coach.

“I thought Deshea did an excellent job with him,” Holmes said. “And I expected nothing less. But, yeah, I’m very excited about Terrion.”