At 28 years old, Jamaal Charles is smack dab in the middle of his prime.

But no running back — even elite ones like Charles — can truly live up to their potential without a well-oiled offensive line, something Charles hopes the Chiefs’ group is better equipped to be this year.

“It was rough,” Charles said with a laugh Wednesday, when asked about last year’s offensive line. “But at the end of the day, this is the National Football (League). You get paid to do your job.”

Charles did that a year ago, when he racked up 1,324 yards from scrimmage and 14 touchdowns.

However, those numbers were down from his 2013 campaign, when he racked up 1,980 yards from scrimmage and 19 touchdowns behind a unit that included veterans like left tackle Branden Albert, center Rodney Hudson and right guard Geoff Schwartz. All are now playing elsewhere.

“It was really rough last year, but at the same time, with that rough line we had, we added experience and (can) win more games than we won last year,” Charles said. “We won (nine) games with an average line.”

That line, which featured only one player who started at the same position he did in 2013, will have a different look this year. Gone are left guard Mike McGlynn, who struggled mightily in 14 games, and right tackle Ryan Harris, who started 15 games.

Hudson, the line’s top performer last season, is gone too after bolting for Oakland via free agency.

This year’s group, at least for now, looks like three-year starter Eric Fisher at left tackle, two-time Pro Bowler Ben Grubbs at left guard, 2015 second-round draft pick Mitch Morse at center, second-year starter Zach Fulton at right guard and fourth-year pro Jeff Allen at right tackle.

Those guys made up the first-team unit on Wednesday for the fifth straight day, and Charles likes the look of it.

“I’m getting comfortable with the group,” Charles said. “I feel like Grubbs and Fish, they’re building a chemistry. Then you’ve got Jeff (who) moved (to tackle) and Zach.”

Charles said he could tell Allen, a full-time starter in 2013 who basically missed all of last year because of an elbow injury, is excited to be back on the field. Allen started this year’s camp as the starting right guard but was recently moved to first-string right tackle when Donald Stephenson was moved to second-string left tackle.

“I think Jeff, he wanted to play,” Charles said. “He missed football last year, I could see it in his eyes. I had that same feeling. He’s just happy to be on the field. He wants to do whatever it takes to get a job, and that’s what it’s about.”

Fulton, a sixth-round pick in 2014, went through the typical rookie struggles but started 16 games a year ago. He opened camp on the second string but is back in the starting lineup.

“His rookie year is out of the way,” Charles said. “He got more comfortable with the offense.”

Charles, meanwhile, gave Morse a vote of confidence, even if he hasn’t gotten to know him on a personal level yet.

“I forgot (No.) 61’s name. … But I feel like he’s experienced, he just came off a good year with Missouri and played a nice career with Missouri,” Charles said. “He’s ready. He’s not very experienced, but he has experience in the past playing at a high level in the SEC. So I feel comfortable.”

Grubbs, a nine-year veteran who was acquired from New Orleans for a fifth-round pick this offseason, potentially represents the bigger immediate upgrade on the line, as the 31-year old was recently selected to the Pro Bowl in 2013.

After seeing Albert walk via free agency a year ago, Charles is happy to have an established veteran with a pedigree on the line again.

“It’s going to be even better with having a great talent at left guard,” Charles said. “Just having a Pro (Bowler gives you) that confidence.

“Grubbs, he reminds me of Brian Waters. And Brian Waters was a great guard for the Chiefs for a long time, and that’s what we need, guys like that.”

But even if Grubbs far outperforms McGlynn this year — a reasonable assumption — the four other guys, Fisher, Morse, Fulton and Allen, all have plenty to prove.

The good news, quarterback Alex Smith noted Wednesday, is that that last year’s line struggles, at least in part, had to do with the fact McGlynn, Harris and Fulton were all were thrown into the starting lineup together after week one, when a combination of injuries and a suspension to Donald Stephenson crushed the depth of the group.

Harris was signed at the start of camp, while McGlynn was signed at the end of the preseason.

“It was tough last year in a sense with just the moving parts,” Smith said. “We had a bunch of guys that came in late. We were trying to fit it together, even through camp. You’re picking up guys that were stepping in and playing.”

Smith said this year’s group, barring any additional signings or demotions, should benefit from practicing and working together throughout camp.

“I think this year we are a little deeper, so I think the pieces are here right now, whereas last year that wasn’t necessarily the case at this point,” Smith said. “I think we have the pieces in place. It’s just a matter of figuring out the best five and what’s that going to be.

“And inevitably, like every year, it’s more than five. You need depth. It’s gonna be seven or eight guys that have to step in and play over the course of the year.”

That is why Stephenson and center Eric Kush, who both opened camp with the first team and are now on the second team, would be wise to remain focused and continue work on their craft. Same goes for veteran guard Paul Fanaika, who signed a three-year deal this offseason but hasn’t yet risen above the second team. Nothing has been locked up yet, especially with four preseason games left to play.

However, the entire unit can take heart that their quarterback is optimistic about the future of this year’s group.

“I think those guys are doing a great job,” Smith said. “They get great work in practice, they go against such a good front. So they get tested every single day, every play. They’ve been doing a great job, so for me, I’ve got enough on my own plate to worry about.”

And their star running back feels the same way.

“It makes me feel good — I feel so comfortable and I’m happy,” Charles said. “I’m so excited to have a line. When you have a line, that gets you excited. That gets you wanting to play. (You) want to stay on the field. You want to give your all.