That may change in the next two weeks.
Peterson is due a $750,000 roster bonus on March 16 and could earn another $2.05 million in bonuses should he play the entire 2018 season, in addition to his $1.05 million base salary.
Paying a backup running back more than $3 million may not be in the Cards' plans this offseason, especially when they can save $2.625 million in cap space by cutting Peterson.
Until that happens, the idea of two of this generations' most dynamic running backs -- one still in the beginning of his career and one on the downslope -- is alive.
"I think it's one of those things in this day and age you have to have a couple of backs," general manager Steve Keim said. "David can't play every snap, even though he's a guy who has third-down value. You have to have someone who can take the load off."
Will Peterson be that guy? Keim hinted Peterson isn't the type of well-rounded back the Cardinals want.
"There's no doubt Adrian still has some juice left in the tank, particularly from a run-skill standpoint -- he still runs with a lot of anger and aggressiveness and has the type of contact balance you look for in that position," Keim said. "But in today's day and age, we all know you have to be able to catch the ball out of the backfield and do a lot of different things.
"Versatility is a key."
Peterson's running history has been established, paving the way for his induction to the Pro Football Hall of Fame after he retires. But as a receiver, Peterson hasn't produced the type of numbers Johnson has.
Last season, Peterson caught 11 passes for 70 yards -- including nine for 66 with the Cardinals. In his last 16-game season in 2015, Peterson caught 30 passes for 222 yards. In Johnson's last full season, in 2016, he caught 80 passes for 879 yards.
For his career, Peterson has 28 drops.
Keeping Peterson would reduce Arizona's options in the passing game out of the backfield but would still give the Cardinals sufficient depth on the ground behind Johnson. However, coach Steve Wilks wouldn't address Peterson and Johnson specifically.
"Well, I think when you have depth that's great," Wilks said. "You always want to be able to have multiple guys in certain positions so that's going to help. And also let me allude to, we're going to do whatever it takes to win the football game, that's my philosophy, that's what I believe in. You're talking about teams putting eight in the box and it's going to be hard to run the football. That's having a system based on what you're getting and now we have to go over the top."