SPARTANBURG — Until the Panthers put pads on next week, it's going to be hard to get an accurate read on the competitions for spots on the offensive line.

But with the emphasis in the first week of camp on installation and flexibility, they at least know they have veterans who can fill multiple roles, because they made it a priority to go get them.

Cameron Erving and Pat Elflein were the first two free agents to agree to terms with the Panthers this offseason, so adding guys with their kind of positional flexibility was obviously important to them.

Erving's working with the first team at left tackle during camp, but has played all five spots in his NFL career. Elflein's spent most of his time in camp at left guard with the ones, but has also gotten some looks at center.

So when head coach Matt Rhule said this week it was too soon to know which players would fit where, both Erving and Elflein knew the drill.

"Playing offensive line is already hard, and switching back and forth, its tough too," Elflein said. "You can't just focus on one thing. But the basic fundamentals of the position are pretty similar across the board, so if you can hone in on those, you give yourself a chance to be successful whichever one you're at."

Elflein's ability to play center also adds a degree of security as the Panthers try to build up front, since center Matt Paradis is entering the final year of his contract.

For Erving, the challenge to be ready for anything includes sharing time with the team's highest-paid blocker.

Recently extended right tackle Taylor Moton has taken a decent amount of work on the left side, as they consider him moving away from his comfortable spot. That might make other players uncomfortable, but Erving knows not to take it personally.

"Man, all I can control is me," Erving said. "I don't really care what anybody says, I've heard it all. I could give two effs about what anybody says about me. People in this building and this organization know what I bring to the table, and what I bring to the team, and it's more than just on the field.

"I embrace every challenge that's placed in front of me. Taylor's a great guy and a great teammate and helps me, and I help him. I've seen a lot; he's done the same. We just try to pull for each other and progress our game."

As a former first-round pick of the Browns who is on his fourth team, Erving knows his reputation is of a journeyman swing tackle, not necessarily someone you build around. But as he stressed, his experience working in a number of situations with a number of top-level linemen (he mentioned things he picked up from players such as Joe Thomas, Mitchell Schwartz and Tyron Smith, among others) help him bring knowledge to the Panthers regardless.

"I've bounced around and played a lot of positions on a lot of teams," Erving said. "A lot of people look at that as a negative thing, but it is what it is.

"I gained experience from great players throughout my career. . . .Those guys, you learn something everywhere you go. I've been blessed to be in the position I'm in, and all I can do is embrace the challenge in front of me every day."

Between them, they have 96 career starts in the league, and adding guys with experience was intentional, since they brought in three rookies to the mix.

And since they have some experience, they know the real challenge will begin next week, when the contact is live, and the real evaluation can begin.

"Yeah, everybody's itching to put the pads on again and hit somebody, if I'm being honest," Erving said. "Everybody in the NFL, if they're honest, they'll tell you you're not really ready until you put them pads on.

"Offensive linemen, defensive linemen, you've got to hit guys, put your body on somebody, and move them."

And then, based on what the coaches see, they also know they might have to move.