EDEN PRAIRIE — The Minnesota Vikings had a critical role to fill on their defense this season following the departure via free agency of nickel cornerback Captain Munnerlyn.

Mackensie Alexander was a second-rounder from the NFL draft pick factory at Clemson last year, with the potential to step up. Terence Newman was back for a 15th season in the league, always a trustworthy option even if his skills are more limited at age 39. There were, though, no guarantees of a seamless transition.

Three-quarters of the way through the schedule, the Vikings (10-2) are thriving behind a defense that has developed into even more of a dominant, unselfish, synchronized unit under the direction of head coach Mike Zimmer.

“I really like this group. I think we have a lot of good playmakers,” Zimmer said Wednesday, as the Vikings began preparation in earnest for their upcoming game against the Carolina Panthers.

“But I like, probably more so, the confidence they play with and the desire to compete each Sunday. This group really likes to go out and compete and prove that they are good.”

The backbone lies in the secondary, where Alexander, Newman and an improved Trae Waynes have ably complemented standout Xavier Rhodes to give the Vikings as much quality depth at cornerback as any of their NFC competitors.

“They’re doing a great job, man,” said defensive end Everson Griffen, who’s fourth in the NFL with 12 sacks, and a significant beneficiary of the taut coverage behind him. “They’re locking ‘em down. They’re giving us a great chance to get to the quarterback.”

With starting safeties Harrison Smith and Andrew Sendejo also contributing heavily, never was this strength of the Vikings more evident than last Sunday at Atlanta. The Rhodes-led smothering of star wide receiver Julio Jones highlighted a 14-9 victory over the Falcons. The Vikings are 10th in the NFL in passing yards per game allowed and seventh in passing yards per play against them.

“It all starts with what the secondary does,” Panthers coach Ron Rivera said on a conference call while praising the defense his team will be tasked with trying to move against this weekend.

With Cam Newton and perhaps Aaron Rodgers left to play in the regular season, and the possibility of either of them plus Drew Brees, Jared Goff, Matt Ryan, Carson Wentz and Russell Wilson as opposing quarterbacks in the playoffs, well, there won’t be much room for lapses. There’s been no indication one is coming, either.

This quartet, with three former first-round draft picks and the second-rounder Alexander, is quite the advancement from Zimmer’s first year in 2014. Then, Rhodes was still developing in his second season, Munnerlyn was struggling to learn a new system after arriving from Carolina, and Josh Robinson was never playing up to his athletic potential.

Alexander has had his ups and downs, like Waynes last year, but he has learned to embrace playing the slot that Munnerlyn occupied before he returned to his original team, the Panthers.

“He’ll have moments where he won’t do what he is supposed to do all the way, but he’s getting a lot better with it,” Zimmer said of Alexander. “I think he’s starting to understand where his help is, when we have man or zone, different things, understanding routes.”

Waynes has become one of the surest tacklers at his position in the NFL and held his own while being targeted more often than Rhodes, who has been ignored more and more by wary quarterbacks.

“Each game I tell him, ‘Make them change their minds,’ if they’re ever throwing your way,” Rhodes said, “and he’s starting to do that.”