Cardinals running back David Johnson is hoping to gain 1,000 yards rushing and a 1,000 yards receiving.

Just what is a David Johnson worth?

He's worthy of being the centerpiece of an offense, as a threat to gain both 1,000 yards rushing and a 1,000 yards receiving and capable of getting 30 touches a game. He's valuable to a team's offensive efficiency, creating matchup problems and three-down availability with his dual abilities as both runner and pass catcher. He's priceless to a fan base which loves a modest superstar.

His value on a contract … well, that's soon to be seen.

"The scary thing about David Johnson is that he has three assets that not many people have," General Manager Steve Keim said. "Number one, he's got a rare work ethic. Two, he's got freakish genetics and rarely do you find a guy with freakish genetics and rare work ethic. Usually, they have to work hard just to compete on the NFL level.

"And then the number one asset he's got that I think will make him continue to get better as a pro, is humility. But even with all the attention and being in the limelight, he's still able to evaluate and be critical of himself."

Johnson, who will turn 26 in December, isn't sure (or at least, isn't saying) exactly what he's worth, monetarily or otherwise. As usual, he downplays what he has done.

"I did have some success last year," Johnson said. "I did start showcasing my abilities. But I feel like I have a lot more improving to do."

His humble nature is genuine, locked in from his third-round roots. It isn't going away. "No, man," Johnson said. "I have so much to learn."

If that's true, how much more could he be worth?

Johnson is eligible for a contract extension for the first time after this season, his third in the league. His rookie third-round contract expires after the 2018 season, paying him $615,000. In the offseason, Johnson said he was watching the negotiations of Steelers running back Le'Veon Bell, who is under the franchise tag. Bell, if he signs his tender offer, would make a little more than $12 million this season. When Johnson made his comment, Bell still had a chance to sign a long-term deal. Now, Bell will have to wait until after the season, and no new market for running backs has been set.

"I don't pay super-close attention (to Bell's situation), especially since the season started," Johnson said. "I'm trying to focus on this team. I want to get to know the playbook so well that I am able to do more on the field as a running back and a receiver."

(Johnson said he had not heard of Bell’s hope that he be paid the equivalent of a No. 1 rusher and a No. 2 receiver, given his stats – stats that certainly parallel Johnson's.)

Johnson's push for his second deal certainly won't be hurt by how much the Cardinals lean on him. Coach

Bruce Arians has talked about getting Johnson 30 touches, which as an average seems high (Johnson led the league with 23.3 a year ago). But mixing in receptions with 20 carries is a different thing than 30 rushing attempts.

"Run the ball 30 times, you're not going to last long in this league," Arians said. "We all know that. But 20 runs and not all up-the-middle-type things, getting his hands on the ball where he can create in space, those tackles, they don't take much out of you."

Johnson sees no reason why he couldn't get around 30 plays.

"It's a whole different thing when you are catching and having to try to avoid a cornerback or safety then trying to avoid a D-tackle who is 300 pounds or a linebacker who is 250," Johnson said. "That's a lot less load on you. As a receiver, it's usually about two guys trying to tackle you. As a running back, it's like seven guys trying to tackle you in the hole."

Johnson said he felt "good" physically all the way up to the last game last season, young enough to handle a heavy load. His knee injury in the finale didn't change that feeling, other than to make him appreciate how quickly it could end.

That's when you really know what a David Johnson would be worth. If he wasn't there.

"The most motivating part is to be remembered as a great player, a great person," Johnson said. "That's the thing. The stats, the individual stuff, most of the time, that helps the team."