EAGAN, Minn. — In the year before Vikings Head Coach Mike Zimmer arrived in Minnesota in January of 2014, the Vikings gave up a league-worst 30 points per game.

In the six seasons since, Zimmer has cultivated and crafted one of the league's stingiest units, as Minnesota has ranked no worse than 11th in points allowed per game.

In fact, the Vikings have had one of the best units in terms of keeping opponents from scoring, as Minnesota has finished in the top nine in points allowed per game in each of the past five seasons.

That run was highlighted by the 2017 unit that finished atop the NFL in both points allowed (15.8) and yards allowed (275.9) per game.

Yet as the Vikings prepare to navigate the 2020 offseason, there is the potential for major changes for the first time under Zimmer's watch.

Some decisions will play out over the next few months, while others are more immediate.

Here is a look at three main questions facing the Vikings defense in 2020:

1. Who is the defensive coordinator?

Minnesota will have a new defensive coordinator going forward, as Zimmer announced Monday that George Edwards will not return in that role.

Zimmer explained the decision to part ways with Edwards:

"He was at the end of his contract, so it was kind of a situation where it was probably best," Zimmer said.

Edwards had been on Zimmer's staff as the defensive coordinator since 2014. The pair first coached together in Dallas from 1998 to 2001.

Edwards was Washington's defensive coordinator in 2003, and held the same role in Buffalo in 2010 and 2011. He was Miami's linebackers coach in 2012 and 2013 before coming to the Vikings.

And while Zimmer calls the defensive plays, he praised Edwards' impact over the years.

Zimmer said he plans to evaluate things before making a hire at defensive coordinator.

"The same thing that I was just talking about with the offense … I'm going to take some time to think about it, and go from there," Zimmer said.

Zimmer's defensive staff has largely remained untouched since 2014.

Edwards was the defensive coordinator since then, while the three position coaches — Andre Patterson (defensive line), Adam Zimmer (linebackers) and Jerry Gray (defensive backs) — have also each been here since 2014.

After Zimmer's media session, NFL Network's Tom Pelissero reported Gray and the Vikings are parting ways.

Vikings assistant defensive line coach Robert Rodriguez has been with the team since 2015, while defensive assistant Jeff Howard joined the Vikings in 2013. Nick Rallis, the defensive quality control coach, just finished his second season in Minnesota.

2. What does the secondary look like?

Zimmer began his NFL coaching career in 1994 as an assistant defensive backs coach in Dallas, as he has a deep affinity for his players in the secondary.

But there is a chance that the group looks different in 2020 as multiple players are set to have their contracts expire at 3 p.m. (CT) on March 18 with the start of a new league year.

Safeties Anthony Harris, Jayron Kearse and Andrew Sendejo are included in that group, as are cornerbacks Mackensie Alexander and Trae Waynes.

Zimmer said Monday that there is a possibility the Vikings secondary has some new faces going forward.

Zimmer said he plans on giving coaches and staff a week or so off before coming back to evaluate the roster. He added that he will then have his usual conversations with Vikings General Manager Rick Spielman, Vikings Assistant General Manager George Paton and Rob Brzezinski, the Vikings Executive Vice President of Football Operations who handles the salary cap.

"I think we'll have to make some tough decisions in a lot of areas, not just in the secondary," Zimmer said. "Again, we're going to have to sit down with Rick and Rob and George and talk about where we're at with salary cap, where we're at with the age of players, who we feel like are going to be core players for us in the future, and kind of make all those decisions.

"But again, we've always done this player evaluation thing with the coaches right after the season," Zimmer added, "and I just felt like it's not the right time and we should get away from it so that we're not biased in whatever happened in the last ball game or the last two weeks or whatever it was."

Zimmer said this is the first time he will give his staff some time off before returning to recap the 2019 season and look ahead to 2020.

Harris joined the Vikings as an undrafted free agent in 2015 and blossomed into one of the league's best safeties. He has started 31 games for the Vikings, including 23 in the past two seasons.

Harris tied for the league-lead with six interceptions in 2019 and has nine picks in the past two seasons. He also had a forced fumble and 11 passes defensed in 2019.

Kearse was a seventh-round pick in 2016 and has made five starts in 62 total appearances for the Vikings. He made clutch fourth-quarter plays in back-to-back-weeks at Dallas and against Denver, but was banged up at the end of the season and did not play Saturday in San Francisco.

Sendejo was with the Vikings from 2011-2018. He began 2019 with Philadelphia but returned for the final half of the season. A starter at safety before Harris' ascension, Sendejo is a solid special teamer who filled in at slot cornerback in the playoffs due to injuries.

Alexander endured some ups and downs early in his career after being a 2016 second-round pick out of Clemson, but matured into a solid nickel cornerback over the past two seasons. He battled injuries over the years — Alexander has never played a full 16-game season — and missed both of Minnesota's playoff games with a knee injury.

Waynes was a first-round pick in 2015 out of Michigan State who has tallied seven total interceptions in 53 starts for the Vikings. A full-time starter for the past three seasons, Waynes was also one of Minnesota's top run defenders on the outside.

3. Does the core group of veterans stay together?

Minnesota's defensive success over the past six seasons can be traced to both talent and scheme.

But the continuity on that side of the ball has also been a big factor, as nine starters have been with Zimmer for at least five consecutive seasons.

Everson Griffen, Linval Joseph, Anthony Barr, Harrison Smith and Xavier Rhodes were either brought in by Zimmer in 2014 or were already with the Vikings before that. Danielle Hunter, Eric Kendricks, Waynes and Harris all joined the Vikings in 2015.

Minnesota endured an up-and-down performance on defense in 2019, as the unit finished 14th in the league with 341.6 yards allowed per game. But thanks to a red-zone defense that finished second in the NFL at 43.75 percent, the Vikings allowed just 18.9 points per game, good for fifth in the league.

Yet as season No. 7 under Zimmer sits on the horizon, the Vikings head coach used a tone Monday that indicated perhaps not everyone that has been with him since seemingly forever will return in 2020.

"It's definitely hard because I really respect these players. These players and the ones that have been with me for six years now, they've busted their rear ends and they've done everything I've asked them to do," Zimmer said about the possibility of roster turnover. "That's always going to come into play … how you feel about them as a person. But I think you really have to look at, 'Alright, he's a great kid. He's worked his rear end off. We love him here. Can he still play? If he can still play, at what level is it?'

"Then you have to match that with the salary and every other thing and then match it with the salary cap, so there's so many different variables. I've been extremely fortunate here that the players that have been here, 99 percent of them are outstanding people," Zimmer added. "They work really, really hard. If you guys saw the way that this team approaches each day, each week, going into meetings, going to practice and saw all those things, you'd be very impressed with the way that they handle themselves."

Griffen addressed his future with the organization Monday and said he wants "be a Viking for life," but also understands the business side of it. Joseph has dealt with injuries the past two seasons but is still a dominant force on the interior when healthy.

Hunter has recorded 14.5 sacks in each of the past two seasons after signing a multi-year contract extension in June of 2018. He was recently selected to his second-straight Pro Bowl.

Shamar Stephen spent 2014 to 2017 with Minnesota before playing for Seattle in 2018. He re-joined the Vikings in 2019 and is known as an unheralded defensive tackle, especially in the run game.

Barr, who was Zimmer's first-ever draft pick in 2014, chose to re-sign with the Vikings in free agency in the spring of 2019. Kendricks was an All-Pro in 2019, and signed a multi-year contract extension in April of 2018.

Smith, who was recently named to his fifth consecutive Pro Bowl, has been one of the standard bearers at his position for most of the past decade. His 23 career interceptions rank seventh in team history, and he sits atop the list with four pick-sixes.

Rhodes was an All-Pro at two positions in 2017 as he was one of the NFL's best shutdown cornerbacks. He has battled both injuries and inconsistent play over the past two seasons.