EAGAN, Minn. – Most years, rookies get their feet wet in the NFL over the course of four preseason games.

But in the case of 2020 and the cancellation of exhibition games due to the COVID-19 pandemic, it was sink or swim in Week 1.

Talk about a tough first test for Minnesota's young cornerbacks group in Aaron Rodgers and the Packers. The Vikings defense struggled to put any pressure on the future Hall of Famer, which Vikings Head Coach Mike Zimmer attributed partially to quick passes.

"Most of the time the ball was out in two-and-a-half seconds. They quick-counted us one time on third down, caught us in a couple man-coverage things where they had pick routes. There were some of those situations, too," Zimmer told Twin Cities media members on Monday. "But he was getting the ball out pretty quick a lot of times, unless he got out of the pocket or unless it was maximum protection."

It's also fair to say that there may be some growing pains for young corners, whether that be second- or third-year players with limited experience or 2020 draft picks Jeff Gladney and Cam Dantzler.

"We still have to work technique and things like that, and there were some issues where they should have been in a different alignment than they were," Zimmer said. "Those kinds of things will show up as we continue to move forward. But I can do a better job with them, for sure."

There's one game down and 15 to go in the regular season, so there's no choice but to keep moving forward. Asked how the quick turnaround changes the teaching process with young defensive backs, Zimmer said, "You just stick with it."

"You just kind of keep going and keep trying to harp on them to do their best and iron out the little mistakes that they did make," Zimmer explained. "Again, it gets back to technique a lot of times and then alignments, making sure you're in the proper alignment and [using] the proper hand placement. But it's good to find out where we were and where we have to go from there."

Here are four other things Zimmer discussed during his media session:

1. Early evaluation of Dantzler

Zimmer was asked his impressions of Dantzler, who started at outside cornerback opposite Mike Hughes and played 64 (82 percent) of Minnesota's defensive snaps in his first NFL game.

The head coach reiterated the learning experience for rookies.

"There's 25 seconds left in the half, and he's trying to play bump-and-run on the wide receiver instead of understanding the situation there," Zimmer said. "Other than that, I thought he did a pretty good job. He missed a tackle early in the ball game that ended up being about seven yards. He contested a catch by [Davante] Adams early in the ball game that he was all over, just didn't get the ball out. He had some good moments in there, it just gets overshadowed by the [45-yard touchdown] right before the half."

Gladney, whom the Vikings drafted 31st overall, played nine snaps on defense and six on special teams.

"We had three other guys playing. But we did use him some later in the ball game, and I thought he did well," Zimmer said.

2. The good, the bad and the ugly

After reviewing tape of Sunday's 43-34 loss to Green Bay, Zimmer pointed out positives and negatives from the team's first outing of the 2020 season.

He re-emphasized the offensive struggles in the second quarter and the fact that a lopsided time-of-possession battle "kind of messed things up" in the first half.

"A lot of that was, defensively, we couldn't get off the field," Zimmer said. "On third downs, I don't think we did a good enough job there. [Rodgers] made some great throws. We let him out of the pocket a couple times, didn't get much pressure on him. Then when we jumped offsides three times on third downs, that didn't help the situation any. We didn't play very well defensively. It was a new experience, I guess, for a lot of those guys coming in there and getting ready to go.

"But there were some good things," he continued. "I thought our protection was pretty good for the most part. It was nice to see Kirk [Cousins] move in the pocket a few times. In the second half, offensively, I thought we played really well. Moved the ball pretty good, scored some touchdowns, got some 2-point conversions. Like every game, there's some good and some bad."

3. A look at the safety

Early in the second quarter, Packers cornerback Jaire Alexander streaked untouched to sack Cousins in the end zone for a safety.

The Vikings used play-action and faked a handoff, but Alexander got to Cousins from the quarterback's blindside.

Zimmer weighed in on the costly play:

"What I was told was that [Alexander] thought it was a run, so he just kept coming," Zimmer said. "We have a guy responsible for [covering] him, but I'm not going to mention who it would be. And he didn't see him."

4. Positives from the pass catchers

Although the Vikings offense hit a lull in the second quarter, Zimmer saw some bright spots from the receiving corps.

"I thought they did well. Adam [Thielen] played like he always does, made some really good catches," Zimmer said of Minnesota's leading receiver with 110 yards and two scores.

"I thought Bisi [Johnson] played well. I thought Justin [Jefferson] did some nice things," he added.