Fifteen minutes after the Vikings wrapped up Tuesday's opening of a three-day mandatory minicamp at TCO Performance Center in Eagan, defensive lineman Dalvin Tomlinson was the last veteran on the field. He held a blocking pad, walking second-year teammate T.J. Smith and rookie Tyarise Stevenson through pointers of playing in the new 3-4 defensive front.

"Just some techniques and block recognitions," Tomlinson said. "Like different tendencies you can see to pick up on. In formations, if the [running] back is away [from you], loosen up a little bit because you got more space, he's coming toward you."

The Vikings' switch to a 3-4 defensive front under coordinator Ed Donatell, which the franchise hasn't featured in decades, is no small change. Tomlinson, entering his sixth NFL season, is the only interior defensive lineman with extensive experience going back to his time with the Giants and at the University of Alabama.

Just about everything, from the playbook to where and how interior defensive linemen line up, is different.

"Even the smallest thing like your stance," Tomlinson said. "You have to change that, because you're playing blocks differently. You have to use a little bit more power than hitting gaps and stuff like that. You have to be ready to take on those bend blocks and those double teams a lot more on the inside."

Defensive line coach Chris Rumph is transitioning a room full of 4-3 defensive tackles with Tomlinson's help. Even free agent signing Harrison Phillips, the fifth-year nose tackle, is learning from Tomlinson as he transitions from Buffalo's 4-3 front.

"[Tomlinson] knows the ins and outs," second-year defensive tackle Jaylen Twyman said. "How to rush in this defense, how to play 4i [aligning on the offensive tackle's inside shoulder]. Been leaning on him a bunch."

Officials, Fleck spotted at minicamp

The Vikings' mandatory minicamp — the final practices of the offseason — resembled the previously voluntary organized team activities (OTAs) under new coach Kevin O'Connell. There wasn't a ton of 11-on-11 work outside of a few series, but quarterbacks Kirk Cousins and Sean Mannion did participate in a hurry-up drill at the end capped by field-goal attempts from kickers Greg Joseph and Gabe Brkic.

Joseph, the incumbent, and Brkic, the undrafted rookie, furthered their competition by each missing a try; Joseph failed from 46 yards and Brkic from 48 yards. Joseph ended the session by clearing the uprights from 50 yards.

Two appearances changed the look of minicamp: Ron Torbert, referee of last year's Super Bowl, and a crew of officials oversaw practice. Gophers coach P.J. Fleck was also in attendance, chatting with O'Connell on the sideline.

Rookie safety Lewis Cine, the first-round draft pick who has worked mostly with backups this spring, got some first-team work alongside safety Harrison Smith during 11-on-11 reps.

Three in the mix for right guard

All but two players — rookie tackle Vederian Lowe and center/guard Austin Schlottmann — were spotted at the mandatory practice. Second-year receiver Ihmir Smith-Marsette remains sidelined with a walking boot on his right foot. Linebacker Ryan Connelly (knee) and receivers K.J. Osborn (undisclosed) and Blake Proehl (knee) rehabbed with trainers on a side field.

The shorthanded offensive line led to former Minnesota State Moorhead guard Chris Reed taking second-team center reps while Jesse Davis worked almost exclusively as the first-team right guard, where there is competition this summer between Davis, Reed and second-round rookie Ed Ingram, according to offensive line coach Chris Kuper.

"We got two vets who've played a lot of football, have seen and heard a lot of this stuff," Kuper said. "They're helpful in the room for me and them. A rookie that we're all kind of bringing up. They'll all get a chance, get a shot at the opportunity and I think however it shakes out, we're going to have a really good player."

Edge rusher Za'Darius Smith was participating after being held out during last week's OTAs because of an undisclosed injury.

Wilson getting busy

Veteran receiver Albert Wilson, who signed a one-year deal last week, remained busy during his third Vikings practice. Despite having no experience at punt returner in an NFL regular season, Wilson jumped into that competition and fielded kicks alongside receivers Jalen Nailor and Thomas Hennigan. Injured receivers Osborn and Smith-Marsette are also in the mix.

Wilson also caught a touchdown in the flat from backup quarterback Kellen Mond while working as a slot target during 7-on-7 drills.