D.J. Humphries is the youngest player on the Cardinals' roster, but coach Bruce Arians doesn't treat anybody with kid gloves. That was evident this summer, when he expressed displeasure with the maturity level of his first-round pick.

Since then, Arians and the other coaches have taken it upon themselves to give their talented offensive tackle some tough love, and it's beginning to pay off.

"Knee in his ass every day," said Arians when asked what helped Humphries mature. "A foot wasn't going to do it. That's why his nickname's 'Knee Deep.'"

A hyperextended knee sidelined Humphries the past week, but he was back practicing with the team at training camp on Tuesday.

The Cardinals have depth at offensive line. But a first-round pick is expected to play sooner rather than later, and whether Humphries can beat out incumbent Bobby Massie or Humphries would be needed if Massie was unavailable, it's imperative for him to be prepared. Bradley Sowell and Earl Watford have also gotten extended reps at right tackle while Humphries has been hurt.

The tools are there, but Humphries is raw, so the more he dedicates himself to the craft, the better the chances are he contributes as a rookie. At this point, he's followed through on that plan.

"D.J. is making a nice move," Arians said. "Hopefully he can get back out there and go as well as he was. He's gotten serious about this stuff. It's not college anymore."

NO PRACTICE, NO EXPANDED ROLE FOR DAVID JOHNSON

Third-round pick David Johnson is still sidelined by a hamstring strain, and the longer it takes him to recuperate, the harder it will be for him to make an impact this year.

"(It's) killing him," Arians said. "There's no way a rookie is going to play in September and miss training camp. There's just no way in a hell I'm putting him out there. Not in any expanded role of any kind."

Running back Chris Johnson has reportedly been offered a one-year contract by the Cardinals – there's no word on whether he will take it – and if he or another veteran is signed, that would also eat into David Johnson's ability to see the field.

Linebacker Shaq Riddick (hamstring) is another drafted player who has missed much of camp due to injury.

NIKLAS, GRESHAM INCREASE WORK

Tight end Troy Niklas (hamstring)was cleared for full practice on Tuesday, while tight end Jermaine Gresham (back) participated in team drills for the first time, catching a touchdown pass in 11-on-11 red zone work.

Running back Andre Ellington (hamstring) and linebacker Sean Weatherspoon (hamstring) wore pads but were limited, while cornerback Shaq Richardson returned to practice.

Still out were cornerback Jerraud Powers (oblique), running back Marion Grice (hamstring), linebacker Darryl Sharpton (hip), tackle Rob Crisp (knee), cornerback Darren Woodard (groin) and tackle Cameron Bradfield (unknown). Powers could be back on Wednesday.

CARDS SIGN A SAFETY

Safety Ross Weaver, a member of the Cardinals' practice squad for 11 weeks last season, was re-signed. Safety D.J. Campbell was released to make room for Weaver on the 90-man roster.