Adrian Peterson stewed on the sideline Monday night in Minnesota, the place he once ruled. He watched Dalvin Cook gash the New Orleans Saints for 127 yards, breaking Peterson’s team record for yards in a career debut, as if to rub in it. Peterson could only watch and learn what everybody else had learned about running backs in Week 1 of the NFL: The position belongs to rookies.

Week 1 may be telling lies. If it told any truth, 2017 could be the Year of the Rookie Running Back.

After one week, three of the top five leading rushers are rookies. Cook rushed for 127 yards on 22 carries, validating the Vikings’ choice to take him in the second round out of Florida State.

The only man who rushed for more yards in the opening week was Kareem Hunt, who erupted for the Kansas City Chiefs in the season’s opening game Thursday night. The third-round pick racked up 148 yards and a touchdown on 17 carries and five receptions for 98 yards and two scores in an upset in New England.

Between Thursday and Monday, rookie running backs burst into the league, both expected and surprising. The Panthers made eighth overall pick Christian McCaffery the centerpiece of their offense, handing him the ball 13 times for 47 yards and throwing it to him five times for another 38. The Jaguars leaned utterly on fourth overall pick Leonard Fournette, who gained 100 yards and scored a touchdown on 26 carries – most in the NFL – and also caught three passes for 24 yards.

Tarik Cohen, a 5-foot-6 dynamo taken out of tiny North Carolina A&T in the fourth round, ran five times for 66 yards and caught eight passes for 47 yards and a touchdown. Cohen was no fluke – the Bears plan to make him a key part of their offense, and his skills catching the ball and quickness make him an ideal fit for a modern passing offense.

The debuts reinforced the recent shift of how NFL teams value running backs. For a time, convention dictated running backs were fungible and therefore not worth wasting a high pick. In 2013 and 2014, no running backs were taken in the first round. The flop of 2012 third overall pick Trent Richardson helped poison the notion of taking backs early.

The league has reconsidered and flipped that wisdom. This year, teams took two running backs in the first round, with Fournette and McCaffrey becoming the first pair of backs selected in the top 10 since 2005. Teams took eight running backs in the first three rounds.

As Richardson became the talisman for avoiding running backs early, Ezekiel Elliott has revived the position. If you can find an effective one, rookie running backs actually present some of the best value in football.

Quarterbacks and offensive linemen develop slowly, usually over several years. Wide receivers tend to start slow and make enormous strides in their second and third years. But running back is both less complicated to learn and more punishing on a body. They enter the league near or at their peak, and decline by the time their rookie contract runs out.

If teams can find a good running back in the draft, they can expend the best years out of a player while paying them a minimal salary. The Cowboys used that reasoning when they made Elliott the highest running back drafted since Richardson.

“One of our analytics guys said most backs, they deserve to get their money their first four years in the league, and then they trickle off,” Cowboys Vice President Stephen Jones said last year. “It certainly doesn’t hurt to be paying him (on a rookie contract). Zeke’s exceeded expectations, and it certainly paid off for us as an overall football team.”

The Jaguars and Panthers heeded the lesson, using top 10 picks on running backs. One week is too soon to make any declarations, but the early results suggest they’re on the right side of a trend. Fournette and McCaffrey can thank Elliott for clearing a path for them getting drafted so high.