GREEN BAY -

There were times when the kid at center looked completely clueless. He’d get rag-dolled by the nose tackle. He’d whiff on what should have been an easy block. He’d get his butt kicked in 1-on-1 pass-rush drills.

No, not JC Tretter, although all those things have happened to the Green Bay Packers new starting center during the summer of 2014.

No, the player in question was James Campen, in the summer of 1983.

Nowadays, Campen is the Packers’ offensive line coach, charged with getting Tretter ready for the team’s Sept. 4 regular-season opener at Seattle. But then, he was a guard/defensive tackle at Sacramento (Calif.) City College with Division I and NFL aspirations who’d just been told by the school’s legendary football coach, Jerry Sullivan, that his only chance at amounting to anything as a football player would be as a the guy snapping the ball.

“He said, ‘If you want to accomplish that goal and move on with your career, you need to put the ball in your hand and be a center.’ And I said, ‘What?’” Campen recalled Thursday, as he prepped Tretter for his first NFL game – and first game at center: The preseason opener at Tennessee on Saturday night. “And I’ll never forget, he told me, ‘You’re going to have a couple weeks where it’s going to be challenging for you.’

“‘You’re going to have days where you go, “Why am I doing this? I was a pretty good guard. I was a pretty good D-end. Can I just go play that?” But when you make the commitment, you start doing things, you just have to stay at it.’”

Campen did, earning a scholarship to Tulane and, in 1987, making the New Orleans Saints’ roster. He joined the Packers as a Plan B free agent in 1989 and in 1992, he was at center when quarterback Brett Favre began his NFL-record streak of 297 consecutive starts.

Now, more than 30 years after Campen became Sac City’s man in the middle, Tretter is on track to start at center against the Seahawks, the fulcrum of the five-man unit that will protect Aaron Rodgers.

And just as Campen did in those early days, Tretter has had his growing pains – as expected. The first two days the Packers were in pads, he was manhandled by B.J. Raji and Josh Boyd. But on Day 3, he twice shut Raji down during the 1-on-1 pass-rush period and made a technique adjustment against a particular move that Raji had used effectively against him.

“JC is such a tough-minded kid. You’re not going to rattle [him],” Campen explained. “He’s accepted the coaching, the feedback has been great, and he’s just progressing all the time. It’s just learning it from a fundamental standpoint. As far as assignments, where to go, what to do, the guy’s gold. He just has to get in there and play.

“Every day with the pads, he’s gotten better and improved. It’s a situation where a guy gets to see himself live, in pads against a guy, makes a correction and moves on. He’s done a good job with that. He’s just honing his trade right now and taking steps every day. He’s doing a good job.”

Tretter has a few things working against him. For one, he’s never played center in a game, having played left tackle in college at Cornell after beginning his career there as a tight end. And because of the broken ankle he suffered in his first organized team activity practice as a fourth-round pick during his rookie year last year, he hasn’t played in an actual football game since Nov. 17, 2012, in Cornell’s 35-28 loss to Penn.

On Saturday night, he’ll be at LP Field in Nashville, and while it’s a long way from Cornell’s Schoellkopf Field in Ithaca, N.Y., he’s viewing it as just another milepost on the road to being an NFL center.

“Obviously you don’t want to blow anything up out of proportion. It’s a game, it’s something you prepared for and practiced for,” Tretter said Thursday, during the Packers’ final pre-game media availability period. “If you go into it extremely prepared, you don’t have to worry about being nervous or worried or anything like that.

“It’s another day. And that’s how we’ve treated it. Just building, slowly and steady, doing what we have to do, growing and becoming a better player each and every day. That’s what we’ve done so far, and when we line up the first preseason game, that’ll be part of it.”

For their parts, neither Campen nor head coach Mike McCarthy have sounded particularly worried about Tretter, even after practices where the growing pains are a little more obvious.

“I mean, JC Tretter’s playing center for the first time and it’s obviously in the National Football League in this style of offense. He needs every rep,” McCarthy said after Raji had his way with Tretter late last week. “I can’t tell you if there is someone in the locker room that’s prepared himself as much as he has, and he’ll continue to do so. It’s not [always] going to look clean; our team isn’t clean. Let’s be honest. We’ve missed blocks, we’ve did some wrong things. That’s why you practice.”

And that’s why Tretter knows the four preseason games, starting Saturday against the Titans, are vital.

“It’s a quick, quick learning curve in getting used to everything, and I think it’s all coming together pretty well,” he said. “Obviously, there’s still room to grow and potential to be reached, and that’s something that’s hopefully going to come sooner than later.”

Listen to Jason Wilde every weekday from 9 a.m. to 10 a.m. on “Green & Gold Today” on 540 ESPN, and follow him on Twitter at twitter.com/jasonjwilde.