Vikings insider Ben Goessling

In the spring of 2015, while the Adrian Peterson saga was still playing out, the Vikings did their pre-draft homework on a number of running backs who might be able to succeed the future Hall of Famer whenever his time ended in Minnesota.

The Vikings brought Northern Iowa running back David Johnson to their team facility in Eden Prairie as part of their top-30 prospects event that April, after meeting with Boise State's Jay Ajayi at his pro day.

Johnson profiled as one of the better receiving backs in the class, but after the Vikings used their first two picks on defenders (Michigan State's Trae Waynes and UCLA's Eric Kendricks), the Arizona Cardinals took Johnson 86th overall, while the Vikings drafted LSU defensive end Danielle Hunter two picks later.

Though the Cardinals had been among Peterson's preferred trade destinations — thanks in part to his relationship with receiver Larry Fitzgerald — the Vikings remained firm they would not move the running back, and kept Peterson for what turned out to be 20 more games after his return: a rushing title (and a costly playoff fumble) in 2015, and three games in an injury-plagued 2016 season.

In the spring of 2017, after the team decided to move on by signing former Raiders running back Latavius Murray, it traded up in the second round of the draft to select Florida State's Dalvin Cook, believing he could be the same kind of versatile dynamo Johnson had become by that point in Arizona.

"David's a back that caught everybody by surprise," Cook said. "He's a guy that I watched; when I got in the league, I started to watch more of him. He does the dirty work, he blocks. He does it all. With him getting paid [a three-year, $39 million contract extension in September], that says it all."

Howard Sinker, Star Tribune
David Johnson and Dalvin Cook

Now, as Johnson and Cook hope to share a field for the first time in the NFL, both running backs are at something of a crossroads. Cook, who caught nine passes for 107 yards in the Vikings' first two games, struggled to find open running room before injuring his hamstring in Week 2 against the Packers.

According to NFL Next Gen Stats, Cook has traveled 5.74 yards per yard gained on rushing attempts this season — indicating he's having to dance and do more work to create space for himself than any running back in the league this season.

He missed the Vikings' Week 3 loss, carried 10 times for 20 yards in their Week 4 defeat in Los Angeles before sitting out again last Sunday in Philadelphia. Cook was listed as questionable for Sunday's game.

Johnson, meanwhile, hasn't been the same kind of running back he was in 2016, when he led the NFL with 2,118 yards from scrimmage and 20 touchdowns. He was limited to one game last season because of a wrist injury — the Cardinals replaced him in part by finally consummating a trade for Peterson last season — and has averaged only 3.3 yards per carry this season while touching the ball a modest 17.8 times per game.

While both Cook and Johnson try to do their jobs behind injury-ravaged offensive lines, the Vikings and Cardinals are ranked 31st and 32nd in the league in rushing offense, respectively.

The Vikings found some success running the ball in Philadelphia by pressing the edges of the field with perimeter runs to get away from Eagles defensive tackle Fletcher Cox.

While they will face the league's second-worst run defense in Arizona after playing the NFL's top-ranked run front last Sunday, they could keep elements of their approach against the Eagles to try and spring Cook loose against the Cardinals, assuming he plays.

"I just knew something had to change," Vikings offensive coordinator John DeFilippo said. "We all know the definition of insanity. I thought [offensive line coaches] Clancy [Barone] and Andrew Janocko did a fantastic job. Kennedy Polamalu did a fantastic job in trying some new things out. Obviously, the yardage wasn't there [77 in 23 carries], but there were some effective runs when we needed it. Everyone wants to talk about yards-per-carry, this and that. Can you run it when they know you're going to run it? Can you finish out games? We did that Sunday. We are going to continue doing that moving forward."

They hope to make some progress on Sunday if they indeed see the return of Cook, who was on pace for 1,776 yards from scrimmage last year before he was injured.

"At this point, it's not a prove-it thing," Cook said. "It's about me getting healthier and being able to help my team. Me going out there at 80 percent, 70 percent, I'm not going to be able to help my team like that. We've got a bunch of guys at 100 percent that can help the team win football games. At this point, it's me getting 100 percent so I can go out there and be who I am, be explosive."

He's not the only one hoping for a return to form this weekend.

Ben Goessling covers the Vikings for the Star Tribune. E-mail: ben.goessling@startribune.com