CHARLOTTE – The NFL season has often been described as a marathon and not a sprint, but really it's both.

When the Panthers exited the tunnel and entered the field at Bank of America Stadium for their preseason home opener Friday night, it had been 23 days since they reported to training camp at Wofford College. It also was 23 days before they'll do it for keeps in the regular season opener against the Dallas Cowboys.

While it already feels like a long journey, it's actually only the beginning – and for some, it's already ended. A few camp bodies who reported to Spartanburg on July 25 are no longer on the roster, and two more (cornerback Ross Cockrell and safety Damian Parms) have seen their season end before it began courtesy of a season-ending injury. And over the 23 days that follow Friday's 27-20 victory over the Miami Dolphins, at least one player a day on average - though most of the casualties will be concentrated on cutdown day – will see their journey end as well.

With all that's on the line, even before the Panthers post a single crooked number in the win or loss column, the breakneck pace around the bench area comes as no surprise.

"Fast! Speed!" defensive coordinator Eric Washington screams to his players just before kickoff. "Everything is fast!"

That, in a nutshell, is life in the NFL.

Washington, at age 48, is a rookie of sorts. He's worked the bench area countless times during a tenure as defensive line coach that started in 2011, but Friday was his first game in front of the home fans in his new role.

One of his students, 23-year-old linebacker Jermaine Carter, is a rookie of a different sort. The Panthers' fifth-round draft choice gets the honor of being on the kickoff coverage unit to open the game, and the adrenaline is flowing as if it were the Cowboys game. After a touchback so typical in today's game, Carter comes back to the bench area having taken care of his responsibility but having had really no chance to make a football play.

Still he is breathing heavy, trying to catch his breath after what has to be a breathless moment for a rookie. Soon he's hearing Washington's booming voice again while sitting with his fellow linebackers, getting instruction from first-year linebackers coach Steve Russ as Washington rushes down the line.

"First third down! Excellent job!" Washington says. "Great concentration!"

Within seconds, the continual concentration on what's next pauses for celebration. Defensive players rise from the bench as running back Christian McCaffrey, an expectant rookie this time last year, takes a handoff and turns it into a 71-yard touchdown.

High-fives flow, but nearly before the big screens at either end of the stadium finish showing the replay, the offensive line takes a seat on the bench and begins taking instruction from longtime line coach John Matsko.

"That's the way to get it started up front," Matsko shares with his group, which features two different starters than expected thanks to injuries. One of those starters, left guard Greg Van Roten, made the block that sprung McCaffrey.