Staring intently under the brim of a yellow visor, Sharrif Floyd surveyed the defense without him.

One afternoon last week, Floyd observed his eighth consecutive practice from the sideline as a nagging knee injury has kept him out of the preseason. It’s provided plenty of time to critique his replacement at defensive tackle.

“Technique is up to par,” Floyd said. “He’s been playing some good ball.”

Shamar Stephen is not the listed backup for Floyd, though his name probably should be duplicated on the team’s depth chart. His name shows up behind Linval Joseph, whom Stephen also backs up at nose tackle. He is not going to lead the Vikings’ vaunted pass rush, but he is likely the most important defensive lineman you don’t know about.

Stephen doesn’t possess Floyd’s ultra-quick step at the snap nor does he bludgeon ball carriers quite like Joseph. Even so, Stephen has climbed the ranks as the top backup behind a pair of defensive tackles who both underwent surgery last season. Not bad for a seventh-round draft pick entering his third NFL season.

There’s a reason Stephen was nicknamed the ‘‘Big Fundamental,’’ à la Tim Duncan.

“With the right toughness and the right technique, you can go a long way,” Floyd said.

Through that attention to detail, Stephen proved he could play both interior positions and earned a rotational role last season — all after a rookie year in which he was the only Vikings newbie to appear in every game. Not Anthony Barr or Teddy Bridgewater, but the seventh-round pick.

Stephen was the 17th defensive tackle drafted in 2014, when the Vikings moved the University of Connecticut three-technique tackle to nose guard. A quick study, Stephen beat out veteran Fred Evans for the backup job during his rookie camp. He saw 17 snaps in his first regular-season game, spelling Joseph while a stray bullet wound healed in the starter’s calf.

It would be just the first time the Vikings called upon Stephen, who returned to the lineup this summer after missing 11 games because of turf toe in 2015.

“He’s doing really good,” coach Mike Zimmer said. “Shamar is a strong, big guy that hangs in there and does a lot of dirty work. He’s starting to get better with his pass rush, so that helps. When you see him out here, we missed him a year ago.”

The Vikings especially missed Stephen after Floyd sat out five starts due to knee and ankle injuries. When Floyd’s knee forced him out this summer, Stephen again returned to his old college position, where the Vikings still are developing his pass rush to NFL standards.

Stephen, a former team captain of both his Long Island, N.Y., high school team and at UConn, mostly relies on his actions to speak for him.

“I just think about the work I’m able to put in,” Stephen said. “Just the discipline my parents put in me. I think that goes a long way, because I came from a two-parent home and they instilled great discipline in me, great respect and great work ethic. … Having respect for others and being able to perform and do the right thing as opposed to just saying it.”

Without Stephen, the Vikings leaned a lot, perhaps too much, on 30-year-old Tom Johnson, a situational pass rusher whose 751 snaps last season were the most behind only Everson Griffen and Brian Robison.

So far in the preseason, Johnson has been kept to pass-rushing situations with Stephen the more capable run defender on first and second downs. Oh, and fourth downs. Against the Seahawks on Thursday night, Stephen forced a turnover on downs by upending running back Alex Collins short of the fourth-and-1 marker.

Plays like that would help the Vikings defense achieve the improved run defense they’ve sought this summer. Maybe in time the ‘‘Big Fundamental’’ will become ‘‘Old Faithful.’’

“You can count on him,” defensive coordinator George Edwards said. “It’s money in the bank. He’s going to give you exactly what you ask for.”