GREEN BAY – Christian Ringo knew this wasn’t going to be easy.

As dominant as the 6-foot-1, 298-pound defensive lineman was at Louisiana-Lafayette, Ringo will be the first to tell you the difference between the Sun Belt Conference and the NFL is vast.

His production with the Ragin’ Cajuns – 109 tackles and a school-record 21 sacks – was prodigious and earned him a place on the Packers’ radar as a sixth-round selection in last year’s NFL Draft, but that’s where the assurances end.

Once Ringo arrived in Green Bay, his rookie season was a masterclass in football. Everything was larger from the players to the playbooks. It’s on you to catch the train.

“It’s a new game from college,” said Ringo, who wore No. 97 as a rookie (pictured) but now wears No. 99. “You have to adjust to speed, the strategies. Everything is different.”

Ringo fell short in his first bid to make Green Bay’s 53-man roster last September but learned an important lesson in the process. In spending the entire season on the practice squad, he saw what it took to make it at the next level.

Every in-season practice was his Sunday. Each scout-team rep was another opportunity to develop against the likes of Josh Sitton, T.J. Lang and what he firmly believes is the best offensive line in the NFL.

Ringo did his best to absorb as much information as possible, pulling several late-night study sessions to fully digest defensive coordinator Dom Capers’ complex playbook. Slowly, tension turned to calm confidence.

There were openings to entertain outside offers once he was released during final cuts, but Ringo stayed from start to finish. The Packers showed faith in his talent when they drafted him, and Ringo believes in their plan for his development.

While an active spot never opened up on an already deep defensive line this past season, Ringo felt like a changed player once it ended. Coaches noticed a difference in the rookie, as well.

He trained this offseason back in Lafayette for his second crack at the final 53. As an undersized inside rusher in the mold of Mike Daniels, Ringo focused on increasing his strength and quickness to better utilize his leverage.

“It was a grind, no lie,” said Ringo of his offseason. “As soon as the Super Bowl (ended), I went back to the weights. I did a lot of explosive stuff in the weight room. I did a lot of conditioning back at home.”

Ringo was eligible to participate in the Packers’ rookie orientation camp two weeks ago because he has yet to appear on the active roster. He was one of five returning practice-squad players who attended the two on-field workouts.

Only two months removed from his 24th birthday, Ringo didn’t shy away from being a leader on the practice field. It’s likely the first of many snaps he’ll take next to first-round pick Kenny Clark and fourth-rounder Dean Lowry this summer.

His advice to the draft picks and college free agents was the same: relax. Individually, the camp offered Ringo a large helping of reps on the defensive line and afforded him another opportunity to work through the defensive installs.

Afterward, Head Coach Mike McCarthy credited Ringo and his fellow returning practice-squad players for the quality of the two rookie practices.

“It’s great work for the young men going through it the second year,” McCarthy said. “You want to see them make a jump and see what they’ve accomplished on the practice squad last year and how it carries over.”

Opportunity is aplenty on the defensive line this year with B.J. Raji taking a hiatus from the NFL in 2016 and Josh Boyd getting released, but that’s all noise to Ringo. The future, he says, will take care of itself in due time.

There is a tangible difference going through his second NFL offseason program. With his feet back under him, Ringo knows what’s expected once training camp begins in July.

After making his mark all over the Ragin’ Cajuns’ record books, Ringo hopes the time he’s invested this offseason helps his college production re-emerge at the NFL level.

“I’m definitely excited because I know around this time we’re getting ready for the season,” Ringo said. “It’s a process. Have to wait through the process and try to learn as much as I can and continue to progress until that time.”