FLORHAM PARK, N.J. -- To break up the monotony of training camp, the New York Jets took a little road trip Sunday night to MetLife Stadium, where they held their annual Green & White practice under the lights before a few thousand fans. Thirty minutes before it started, Ryan Kalil was in uniform, pacing the locker room to calm his nerves. Remember, this was a practice, not a game.

"Everybody was making fun of me," he said.

Isn't football great?

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Kalil has played 156 games in his decorated career, including a Super Bowl, and yet he couldn't prevent a case of the butterflies. This was his first practice since coming out of retirement on Aug. 1, when he answered the Jets' desperate call for an experienced center. For seven months, he had been "living the beach life" at his home in Southern California. When he arrived in New Jersey for the 2.0 version of his career, it was assumed he would take a few days to work on his conditioning and make a seamless transition into the starting lineup.

That it took nearly three weeks to get on the field underscores the degree of difficulty in going from the beach to the NFL trenches. The man has a Ph.D. in offensive line play, but there's so much more to his job than snapping the ball to quarterback Sam Darnold.

Kalil, 34, vowed to be ready for Week 1 against the Buffalo Bills, but the calendar is the enemy. He has eight practices and one preseason game to get comfortable with the playbook, learn his fellow linemen (three of whom are injured) and become familiar with the unique style of a running back (Le'Veon Bell) who is being kept in mothballs for the preseason.

The beach never was this stressful.

"It's hard to play when you don't know the plays and you don't know the calls, especially," said Kalil, who spent his first 12 seasons with the Carolina Panthers. "But they're all plays I've done before, all calls I've made before. It's just all different terms, all different code names. They don't have a Rosetta Stone for this. It's like learning a new language."

Center Ryan Kalil, 34 started anew with the New York Jets after spending 12 seasons with the Carolina Panthers. AP Photo/Dennis Waszak

Every play starts with the center. If he botches the snap (which he did twice Sunday night), the play fails. If he makes the wrong line call, it can result in chaos. If he blocks the wrong guy, another guy comes free and blows up the ball carrier or, worse, the quarterback.

Essentially, Kalil is attempting to multi-task while speaking a foreign tongue -- not easy. Ever travel abroad? Then you know the feeling.

"I'm still trying to figure it out myself," he said. "Some of the plays come faster than others. It's tough because you want to play fast. When you can't play fast, you get pushed back. Football, man, you have to be on. It's hard when everything is going right and you know what to do. It's even that much harder when you're playing a little hesitant."

Jets coach Adam Gase said he hopes Kalil can play a series Saturday night against the New Orleans Saints. Right tackle Brandon Shell (knee) could return to the lineup, but guards Kelechi Osemele (strained pectoral muscle) and Brian Winters (shoulder) aren't expected to play until Week 1. It means the starting five will have only a week to practice together, hardly an ideal situation.

The Jets are taking a calculated risk with Kalil, betting he can galvanize the offensive line and accelerate Darnold's development. The organization protected itself by tying a chunk of Kalil's one-year contract to roster bonuses -- $3.4 million of $8.4 million, to be exact. He receives a $118,750 bonus for every game he's on the 53-man roster. He gets an additional $93,750 for every game he's on the active 46. It will pay to stay healthy.

Once Kalil settles in, he will be Darnold's eyes at the line of scrimmage, reading defenses and adjusting blocking schemes.

"He has seen it all," former Jets center and recent Pro Football Hall of Fame inductee Kevin Mawae said of Kalil. "There's nothing a defense can throw at him that he hasn't seen. He has played against all the coordinators they will face this year. He understands [Bill] Belichick's schemes. For him to make the calls based on intuition that Sam Darnold might not have yet, that definitely takes the pressure off [Darnold]. He's played in big games before. He can be a calming influence to a young quarterback."

Right now, Kalil is "playing slow" (his words) and getting into football shape. He knew only one way for more than a decade -- the Carolina way -- and now he's learning a new team, a new system, a new part of the country, a new everything. But it's football, and it still makes his stomach flutter.

"This is why I came back," he said. "I love football, I just do. We all do. It took me walking away to know that it was done, and I really wanted it not to be done just quite yet. So I'm fired up, I really am."