GREEN BAY – The compliment doesn’t get tossed around every day, especially not for a player who’s never been a regular starter in the NFL.

“He’s a complete professional,” Packers’ offensive line coach James Campen said of JC Tretter. “The guy does everything right. Just a true professional player.”

As he enters his fourth season in Green Bay, Tretter’s professionalism has been on display in a number of ways, first and foremost via his perseverance through injuries.

As a rookie fourth-round draft pick out of Cornell in 2013, Tretter suffered a nasty ankle injury in the first OTA practice of the spring. After an arduous rehab, he finally returned to practice in mid-November and was on the active roster in early December, but he never played a snap in a game.

Then in 2014, Tretter was slated to be the Packers’ starting center after Evan Dietrich-Smith departed in free agency. He held down the No. 1 job all through the spring and summer until injuring his knee in the third preseason game.

Replaced by rookie Corey Linsley, Tretter plowed through another rehab, got back on the roster in early November and became a “super sub” at multiple positions the rest of the season.

It was a tough break. The second injury cost him a starting job, and to Linsley’s credit, Tretter hasn’t gotten it back. To Tretter’s credit, he never complained.

Instead, heading into 2015, Tretter dedicated himself to being whatever was needed – a versatile backup, a special-teams blocker – and worked at those tasks as hard as he rehabbed his first two years.

The jumping around on the line late in 2014 became good preparation for his third season. After filling in admirably at center for three games when Linsley was hurt, Tretter stepped in at left tackle in the NFC Wild Card playoff game at Washington as the Packers struggled to adequately replace the injured David Bakhtiari.

Turning in what Campen called an “outstanding” performance, Tretter shook off an early sack/safety and – in true successful O-line fashion – wasn’t heard from again the rest of the game.

“He’s a very confident person, and the reason he allows himself to be confident is he prepares all the time,” said Campen, adding that Tretter has the right marriage of mental acuity and athleticism to play both inside or outside up front.

“He’ll be ready. He’s one of those guys, when his name is called, it doesn’t matter where it is. You can count on him.”

Which brings us to 2016. Tretter is in the same place he was last year – without a starting job, but a valuable, versatile backup. And he’s going about his business in the same head-down, hardworking way, even in the final year of his rookie contract with the future largely uncertain.

“I don’t think too different at all. I’ve kept the same mentality all four years,” Tretter said. “Obviously the first two didn’t go as planned, and last year went a little better. So, you just come to work every day. You prepare and focus, and the contract stuff will work itself out whenever it does.”

Tretter has the skills to start at center in the NFL. He proved that last year, and his ability to move around, while impressive, doesn’t change the fact that center is his best spot.

He could hunt for that starting opportunity after the 2016 season as a free agent, but he’s not getting caught up in that now. As a player whose first two seasons were derailed in ways beyond his control, there’s no point in thinking ahead.

“You have an agent for a reason. He can handle anything like that. You’re focused on playing,” Tretter said. “If you don’t take care of what’s on the field, the contract’s not going to work out for you too well.”

This spring, Tretter took the lion’s share of the snaps at center with the No. 1 unit while Linsley sat out with an undisclosed injury, but Linsley has said he has no concerns about being ready for training camp. Although Tretter enjoyed some consistency of place for the first time in a while, he’s not going to let himself get settled anywhere for the long haul, not after the way last year went.

He may not be needed as a backup tackle again. The first nod there presumably would go to second-round draft pick Jason Spriggs, but there are two tackle spots, and stranger things have happened.

“You have to be ready to move around,” Tretter said. “You never know.”

No, you don’t, but no matter what occurs, Tretter will be prepared. A complete professional always is.