It’s hard to think of a time under the Mike Zimmer and Rick Spielman regime that the Vikings have gone through the offseason with more certainty around the offensive side of the ball than the defensive side.

But that will be the case when the Vikings open their season.

Looking at the Vikings depth chart from the 27-10 playoff loss at San Francisco, the bulk of the talent on offense is set to return in 2020.

Kirk Cousins, Dalvin Cook, C.J. Ham, Adam Thielen, Kyle Rudolph, Riley Reiff, Pat Elflein, Garrett Bradbury and Brian O’Neill are all returning. Thielen didn’t start vs. the 49ers, with Bisi Johnson taking his place, but he did play.

The only starters from that game who aren’t back are receiver Stefon Diggs and guard Josh Kline, with Diggs traded to Buffalo and Kline still a free agent.

But the defense is a completely different story. The Vikings have lost four starters in Linval Joseph, Everson Griffen, Trae Waynes and Xavier Rhodes, and they also lost their nickel cornerback MacKenzie Alexander.

Back are Danielle Hunter and Shamar Stephen on the defensive line; linebackers Anthony Barr, Eric Kendricks and Eric Wilson; and safeties Anthony Harris and Harrison Smith.

But there’s no question that all of those changes on defense are going to present challenges for 2020.

Zimmer said earlier this month that he is getting excited at the idea of working with a lot of new faces on defense.

“Defensively we’re going to have some younger guys, obviously, but I think it’s kind of refreshing to get a chance to work with some younger guys,” he said.

And while the Vikings have to feel good about their linebackers returning, and also a defensive line that has added Michael Pierce to replace Joseph and has Ifeadi Odenigbo, who recorded seven sacks last season and seems poised for a breakout year, the cornerback situation is going to be difficult.

Can they cover?

The Vikings will need Mike Hughes — their 2018 first-round pick who tore a knee ligament as a rookie but could be a standout if completely healthy — and 2020 first-rounder Jeff Gladney to be ready to go in Week 1.

Hughes started three games last season and played in 14 overall, finishing with 45 tackles to go along with an interception.

“We lost a few,” Zimmer said of the veteran cornerbacks leaving the team. “But these guys are talented guys, and you know, as soon as we can get them to understand how we want to do things — they have been good in the [virtual] meetings, but you have to have some guys that can cover.”

Since Zimmer took over as the coach in 2014, the Vikings have been the second-best defensive team in the NFL in terms of points against, having given up 1,848 points in that time. Only the Patriots have been better at 1,724.

But this will be Zimmer’s biggest challenge yet, getting a new defense ready during a unique offseason.

Big replacements

On offense, Diggs will obviously be very tough to replace as he is one of the best receivers in the game, but the fact is that offensive coordinator Gary Kubiak, who is taking over after Kevin Stefanski became coach of the Cleveland Browns, might be more likely to use multiple tight end sets.

That would let him run a lot of plays for Irv Smith Jr., who caught 36 passes for 311 yards and two scores as a rookie last season.

On top of that, you have first-round draft pick Justin Jefferson, who figures to get a real shot to start with Thielen along with returning wideouts Johnson and Chad Beebe and free agent Tajae Sharpe.

Zimmer knows that Diggs is a big loss, but he also said that he thinks the group can succeed without him.

“I think we’re in good shape,” Zimmer said. “Offensively I think we have a good, veteran group of guys. Got some depth. Got some guys to look at on the offensive line. I think Beebe is back healthy again, so the receiving corps should be better as we move forward.”

A rookie starter?

When it comes to replacing Kline, the Vikings will have some linemen to work with, including Dakota Dozier, and they could find a way to shuffle some players around and get second-round pick Ezra Cleveland into the starting lineup.

The coaching staff loved Cleveland all the way through the draft process and were thrilled when the Boise State product fell to them at No. 58.

The Vikings have had a rookie start on the offensive line each of the past three seasons, with Elflein starting 14 games in 2017, O’Neill starting 11 in 2018 and Bradbury taking the most snaps of anyone on the offensive side of the ball in 2019 with 989.

Cleveland said after the draft that he worked in the zone offense in college and that could play a big part in his being able to step into the Vikings offensive scheme quickly.

“Coming from a zone-type offense already, I feel like I have a step above and I feel like the zone scheme comes pretty easy for me and I love blocking in that scheme,” Cleveland said. “It just all fits together. It’s a perfect match.”

When it came to what parts of his game can really fit with the offense, Cleveland said he is an extremely consistent player.

“I come back to athleticism and then heart and consistency. Athleticism is a big part of how I play but I say heart is majority of it,” he said. “You can’t play football if you don’t have the heart, if you don’t love the game. I 100 percent love the game.

“Consistency was also another one, I was pretty consistent offensive lineman at Boise State, starting from a redshirt freshman all the way to a redshirt junior before I ended up coming out. I was there for a reason and now I’m here for a reason. I can’t wait.”

Jottings

Jon Leuer of Orono High School announced his retirement from the NBA on Sunday, after not playing at all in 2019-20. Since the start of the 2000-01 season, Leuer ranked fourth among graduates from Minnesota high schools in NBA games played, with 377. Kris Humphries (Hopkins) played in 800 games from 2004 to ’17; Joel Przybilla (Monticello) played in 592 games from 2000 to ’13; and Devean George (Benilde-St. Margaret’s) played in 581 games from 2000 to 2010, excluding 49 games from his rookie season of 1999-2000. Still active in the NBA are Oklahoma City’s Mike Muscala (Roseville) with 348 career games and Memphis’ Tyus Jones (Apple Valley) with 312.