Instead of testing the free agent market this week, veteran linebacker Derrick Barnes said it was a simple decision for him to re-sign with the Detroit Lions Monday on a new three-year contract.

"I just feel like there's unfinished business here," Barnes told the media after signing his contract Monday at the Meijer Performance Center. "We didn't make it as far as we wanted to last year but we have years to come of great football. My teammates, the coaches, the culture we've built here ... I feel like everything is put together and you can't find that at other places."

Barnes was part of general manager Brad Holmes' first NFL Draft class in Detroit in 2021, and that class has become part of the core to a roster that's transformed Detroit into one of the best teams in the NFC over the last couple seasons. Barnes is now the fourth member of that class to re-sign along with first-round pick Penei Sewell, third-round pick Alim McNeill and fellow fourth-round pick Amon-Ra St. Brown.

Barnes has proven to be a versatile player for the Lions' defense over the years as a SAM linebacker that can play both on and off the ball. He was expected to play a big role last season but injured his knee in Arizona Week 3 that required surgery and forced him to miss the rest of the season.

The year prior in 2023, he had a career year with 81 tackles (42 solo), five tackles for loss, five quarterback hits, a sack and a forced fumble.

Barnes said his former position coach Kelvin Sheppard being promoted to defensive coordinator this offseason was another reason he wanted to return instead of testing the free-agent market.

"We've seen that coming with him," Barnes said of Sheppard's promotion. "He's passionate about the game, loves the game, loves the players, cares about the players. The best thing I love about him is how passionate he is about getting players better.

"That was a big part of my decision coming back to Detroit. He is a guy that anybody would want to play for. Him being the DC, I'm pretty sure every guy here is going to buy in to what he wants."

With Barnes back in the fold, the Lions return all three starters at linebacker with Alex Anzalone at the WILL, Jack Campbell at the MIKE and Barnes at the SAM. That's significant given that the linebacker position is the bridge between the defensive front and the secondary. It's a pretty veteran group of linebackers that will know what Sheppard wants to run and how to implement it best.

"That makes me super excited," Barnes said of the continuity returning at linebacker with veteran Malcolm Rodriguez also in that mix. "We've all seen what the three of us on the field can do, what it looks like. We had something great going before obviously all the injuries. It's amazing to see the kind of pieces and bits of what Shep has ready for us when it comes to us three."

Barnes said health-wise his knee feels good, and he'll be ready for all football activities when the team starts the offseason training program April 22. Before the injury last season, he had only missed three games his first three seasons due to injury.

"It makes me feel good that despite my injury and that situation I feel like (the team) still has a lot of faith in me to be the player they know I can be," he said. "The fact that they had that faith in me to pay me that amount of money coming off the injury is emotional because I know a lot of people don't get this opportunity especially coming off knee injuries. The fact that Dan (Campbell) and them put me in a position to be able to come out and have confidence in me means the world to me."

Barnes thinks they have the pieces to be a really good defense, and Holmes and Co. will continue to add complementary pieces alongside the core in free agency over the coming weeks and the draft next month.

"I feel like when we're a healthy team that we're unstoppable," he said. "I think we can beat any team in this league, and we've proven that. Definitely run it back. One hundred percent."