CHARLOTTE, N.C. -- Protecting quarterback Cam Newton has been a consistent theme for Carolina Panthers coach Ron Rivera since the offseason began.

It could be the theme of free agency.

The Panthers are looking to replace retired Pro Bowl center Ryan Kalil. Not only was Kalil a top performer on the field, he was one of the leaders in the locker room.

Future Hall of Fame defensive end Julius Peppers, who also retired, called Kalil "one of the greatest teammates I ever played with." Left guard Greg Van Roten said Kalil's presence was "invaluable." Rivera compared Kalil to having another coach on the field.

With the exception of time missed because of injuries, Kalil has been Newton's only center since he entered the league in 2011.

So replacing him will be key.

Tyler Larsen, who started 15 games in 2016-17 while Kalil dealt with neck and shoulder issues, is the assumed starter. But when recently asked at the NFL combine about what he's looking for in a center, Rivera left the door open for somebody else.

"We've got something there in Larsen already who has played for us and has done that very, very well," Rivera said. "But we're also looking for a guy who will step up and be the leader in the room -- and not just the position room but the team as a whole. You are looking for a guy with leadership qualities. I thought Larsen did a really nice job when he had his opportunities. I felt very comfortable about that. We'll continue to look at how we can improve our offensive line because as we've said before, we want to make sure to protect our quarterback and to put playmakers around him."

With only $16,725,067 in cap space, the Panthers won't be able to afford one of the top free-agent edge rushers, which is arguably the team's biggest need. But they might be able to afford one of the top centers and shore up the line.

By not re-signing tackle Daryl Williams, they appear committed to left tackle Matt Kalil -- Ryan's younger brother -- successfully returning from a knee injury that sidelined him in the 2018 season. They have right tackle Taylor Moton under contract as well as Pro Bowl right guard Trai Turner and left tackle Van Roten.

Larsen also can play guard, by the way.

The leadership Rivera wants probably won't be found in a rookie draft pick.

That doesn't mean the Panthers won't look for edge rushers and linebackers in free agency as they blend a mix of 3-4 scheme to their traditional 4-3 under Rivera. General manager Marty Hurney just doesn't have the cap space to pursue the top-tier players at those positions, which means the Panthers must take a more conservative approach to free agency.

There's a good chance the Panthers won't sign anybody until the second wave of free agency. Most of their targets could come in the third wave.

But if they do target a so-called name player, here are three potential targets:

Matt Paradis, C, Denver -- He's coming off a fractured fibula that forced him to miss seven games last season. That could drop the price a bit. The 6-foot-3, 300-pound Paradis would eat up a large chunk of Carolina's cap space. But he's the best center available and, at 29, he would secure a need for the next three or four years. It wouldn't be a sexy addition, but Paradis would lessen the loss of Kalil on many levels.

Mitch Morse, C, Kansas City -- For the same reasons above, Morse makes sense. After missing several games because of a concussion last season, his price could be more affordable. He's also 27, so he has a longer-term value than Paradis. Pass-blocking is his strength. He has earned a grade of 70.0 from Pro Football Focus the past four years. That checks Rivera's mark of protecting Newton. Run-blocking hasn't been a strength, which also could lower the price tag slightly.

Trey Flowers, DE, New England -- This would be a pipe dream for Carolina because Flowers (6-2, 265) probably would break the salary-cap bank. But at 26 and with the flexibility to play in any scheme, he could be the long-term answer at defensive end. Add a first-round pick at the position and end would go from a weakness to a strength. Just don't count on this one because the competition for him will drive the price too high.