Aug. 9, 2015, was Trae Waynes’ welcome-to-the-NFL moment.

He was a blazing rookie and prized first-round draft pick when Vikings coach Mike Zimmer pushed him from the comfortable nest of training camp and into the real world of playing cornerback in a league whose rule book favors the guy you’re trying to cover.

It was a valuable, live-action learning experience. One that Zimmer and his peers won’t have with preseason games canceled in this oddball ramp-up to the 2020 season.

The venue on that summer night five years ago was Fawcett Stadium, just outside the front door to the Pro Football Hall of Fame in Canton, Ohio. The Vikings won that preseason opener, beating the Steelers 14-3.

But that wasn’t the story.

The newsmaker that night was Waynes. More specifically his inability to keep his hands to himself. In two periods of action with the backups, he was flagged three times.

He was called for two holding penalties and one 38-yard pass interference penalty. One ofthe holding penalties was declined because Waynes’ guy still caught the ball for a 35-yard gain.

“Part of the thing was I didn’t want to take him out,” Zimmer said after the game. “I wanted to find out what kind of toughness he had when things happen like that and how are you going to fight back and how are you going to respond? I thought he did a nice job with those things. He’s just got to learn some of the technical things about the NFL.”

Unfortunately for the Vikings, Zimmer’s current wave of young cornerbacks won’t see game action until they face Aaron Rodgers on Sept. 13 in a contest that counts.

“It’s a really young group,” said 31-year-old Vikings safety and self-proclaimed “old guy” Harrison Smith. “But I think it’s kind of cool to be a part of that as well because you’re going to see guys get things and catch on and grow.”

Really young became an understatement when the Vikings said goodbye to last year’s top three corners — Xavier Rhodes, Waynes and Mackensie Alexander — along with backup safeties Andrew Sendejo and Jayron Kearse.

On the roster now are 10 corners. Nary a one has more than five NFL starts. The top three are expected to be 23-year-olds Mike Hughes (five starts), Holton Hill (four starts) and rookie first-round draft pick Jeff Gladney. Another rookie, 21-year-old third-round pick Cameron Dantzler, is in the thick of it as well.

That many greenhorns in one secondary certainly sounds ripe for some harmful growing pains. Especially with an offseason limited to virtual learning because of the pandemic.

Maybe. Maybe not, says co-defensive coordinator Andre Patterson.

“It’s probably been a blessing that they’ve had all these virtual meetings,” he said. “They’ve heard the install more than any rookie class in the history of the National Football League.

“So these [rookies] have gone out there [in practice] and they’ve been vocal on making the calls. They know what to do. It’s been really impressive. I think it’s been a blessing in disguise.”

That being said, these guys aren’t playing a video game. They still need practice reps and in-person corrections when it comes to techniques and fundamentals.

“It’s just making sure that we get enough reps and enough practice so we can achieve those things,” Patterson said. “For me, that would be my No. 1 concern.”

Smith hopes the rookies can learn in practice what Waynes learned the hard way five summers ago in Canton.

“They’re coming from college to pros, and the rules are very much not in their favor,” Smith said. “When you play preseason [games], which we won’t this year, I think that’s normally like the most glaring thing [with corners]. The grabbing and illegal-contact penalties. So I think that’s going to be something we have to focus a lot on in practice.”