CHARLOTTE — The nature of the backup quarterback position requires being ready for anything, at any moment.

For P.J. Walker and Will Grier, this offseason was an exercise in such uncertainty, as they didn't know what to prepare for in the coming year — but at least they have experience.

When the Panthers left in January after a 5-11 season, the tepid endorsements of Teddy Bridgewater left a clear sense of doubt about the future. That proved prophetic, though it was three months until the team traded for Sam Darnold, then eventually shipped Bridgewater to Denver.

But with the position unresolved during the winter and spring, players still worked out, so Grier found himself on the field with stars such as Christian McCaffrey and DJ Moore for informal off-site passing sessions, the third-stringer doing the kinds of things starters normally do. For Grier, it was a time to get himself better, without knowing what was happening on the depth chart around him, or who might be on it in the future.

"You've just got to block it out, because you never know what's going to happen any day in this business," Grier said. "Every day, wake up, try to get one percent better, and that's all you can really do. That's not my job to look at any of that stuff, and I don't.

"Obviously, you work out in the offseason, but to me, it's important to be around teammates and throw with guys for a lot of reasons. And we enjoy it. It makes it fun to get around the guys and run some routes. It's been good."

Once Darnold was acquired, and OTAs and minicamp rolled around, the focus has largely been on getting Darnold ready. Panthers head coach Matt Rhule made it a point of emphasis to throw the kitchen sink at all his quarterbacks, and said in June that they had all responded well.

Walker laughed a bit when asked about this offseason, and spending three months not knowing whether Bridgewater would be back or who might replace him. After all, he was on the Colts' roster in 2019 when Andrew Luck abruptly retired during training camp ("The world in general was shocked and confused," he said), so he knows a bit about offseason upheaval.

"I've been part of one of the biggest shocks in football, with Andrew retiring, so this was just another day," Walker said of seeing Darnold arrive and Bridgewater leave. "There was so much happening, so I just tried to focus on me and doing my work.

"We know it's a business at the end of the day. So you know anything can happen. I know that from being in this building, and being in other buildings, day in and day out, you have to be ready for any kind of change. At any point in time, you have to be ready to compete, no matter what. As long as I get to come in the next day and compete, that's all I want, to show these guys this is why I'm here."

Walker got a leg up on the competition last year, getting the nod to start against the Lions when Bridgewater dealt with a knee issue. He helped the Panthers to a win, though there were some rough spots (a couple of interceptions). There were also three picks in the second half of the finale when he replaced Bridgewater against the Saints, but he said he felt like he made significant progress last season, after catching the Panthers' eye during his stint in the XFL.

"It was huge, honestly," Walker said of last year's playing time. "But I built my confidence when I was playing in the XFL. I knew what I was doing, day in and day out, and I was able to show those guys I was able to play.

"I was confident, but I wanted to put my talents on display and show I can play the game. The Detroit game was another step for me. I wanted to go out and compete at a high level, and that's what I tried to do."

Neither of the young quarterbacks benefited from a preseason last year when games were canceled because of the COVID-19 pandemic, and that was a setback in their development.

Grier got a pair of starts late in 2019 when the Cam Newton era was unraveling, but he never got a chance to build on that last summer while learning a new system. The former third-round pick said he thinks he's in a better position to compete this offseason, but he also knows that the coach and general manager here when he was drafted no longer work here.

"I wouldn't say it's pressure, but obviously, the guys that drafted me, drafted me," Grier said. "And they drafted me high and thought highly of me. You get a new staff, and there's a big difference; they weren't here for the draft process. They knew who I was, and you make an impression and work hard, and I think they think highly of me as well. But initially, it's never a comfortable thing to move on from a staff that drafted you and you were close to, but that's the nature of the business."

And for a couple of players so young in their careers (with three NFL starts between them), Walker and Grier already know that the business can change at any time.

And when it does, they know they'll have to be ready to adjust.