JACKSONVILLE, Fla. -- Paul Posluszny is back in the middle of the Jacksonville Jaguars' defense. For Thursday's preseason game against Tampa Bay at EverBank Field, anyway.

Beyond that? Not even coach Doug Marrone knows.

"We're trying to figure out how things shake out," Marrone said. "What's the best starters? What's the best way to go into the season? Who can back who up? Really, that's what's going on.

"We know how Poz can play. We're just trying to figure out what's the best combination for us in base down, and then we're trying to find out what the best combination for us to go into the season is, as far as who is backing who up."

Posluszny has been the Jaguars' starting middle linebacker since he signed with the team as a free agent in 2011 and has been one of the most productive players in Jaguars history. He has led the team in tackles in all but one of his six seasons (missing nine games with a torn pectoral in 2014) and is second in team history with 918 tackles, just 171 shy of all-time leader Daryl Smith.

Posluszny played at a high level in 2016 (team-high 133 tackles, 1.5 sacks, and an interception), yet the team decided to move him to strongside linebacker and make Myles Jack, the team's second-round pick in 201, the starter in the middle. There was no competition, just a meeting in which Posluszny was told he would no longer be playing the only position he's played in his 10-year career.

Jack played only 230 snaps on defense in 2016 but the Jaguars wanted to take advantage of his speed, athleticism and coverage ability by moving him inside. It wasn't an easy transition, especially in terms of making pre-snap adjustments and checks and communicating those changes to the defense quickly. Jack gradually improved and though he missed several tackles and took a few bad angles to get to ball carriers, Marrone and Posluszny both said Jack played at a high level in the preseason opener against New England.

Yet last Sunday they made the switch. Surprisingly, Jack is perfectly fine with it and isn't taking the move as a criticism of his work in practice or his play against the Patriots.

"Absolutely not," Jack said. "Honestly, Poz is a better mike [middle linebacker]. As far as in that base package, Poz is a better mike. He's done it. He's been here for what, five, six years? He's done it. He knows the checks. He knows everything.

"I completely get it. I don't feel any type of way. I think it's what's best for the team. But I want to win at the end of the day so that's all I care about."

The plan for Thursday is for Posluszny to play middle linebacker on first and second down and Jack to play middle linebacker on third downs and in sub packages with Posluszny coming off the field. That's what the Jaguars should have done from the beginning instead of moving Posluszny.

Also on Thursday, since Jack will be on the field all three downs he'll wear the helmet with the radio in it and call the defenses.

Posluszny called the situation at linebacker very fluid and expects it to be that way as defensive coordinator Todd Wash continues to experiment with the lineup.

"Wherever we're playing on that particular day we have to compete at a high level, do the best that we can, and the coaches are going or figure out where our best group is to win," Posluszny said. "So, was I excited when they said, 'Hey you're going to get a shot to play in the middle again?' Absolutely.

"That's what I know the best, but wherever they put me I want to be able to make sure I can do a great job and help the team win."