Cardinals guard Evan Mathis (69) and tackle D.J. Humphries (74) chat during Wednesday's OTA.

Before Evan Mathis signed with the Cardinals this spring, both coach Bruce Arians and offensive coordinator Harold Goodwin had dinner with the veteran guard.

They let him know they wanted him to help fortify the offensive line. But they had another important  request. They wanted him to help D.J. Humphries, the team's 2015 first-round pick who was inactive all season, mature.

"The first meeting, as soon as Evan walked in the room, he mandated D.J. sit next to him," Goodwin said. "They've been working out together every morning in the weight room. From D.J.'s standpoint, he gets to

see a Pro Bowl player work every day, how he works, how he is a professional. D.J. has no choice but to grow up."

Barring something unforeseen, Mathis will be the team's right guard. Humphries will be the right tackle. Going into his 12th season, Mathis said the Cards didn't even have to ask him to aid Humphries because it's something he tries to do anyway.

"It's going well," Mathis said. "D.J. has been very receptive to hearing what the coaches and myself have to say, about our experience and what we have been through."

Humphries agrees it was a natural way for their relationship to develop. Even last year, Humphries said, he tried to glean information from veteran tackles like Jared Veldheer and Bobby Massie as well as a veteran defender like linebacker Dwight Freeney.

Calling himself "super-open" to advice, Humphries knows Mathis provides valuable insight.

"It was one of those, 'He's the vet, I'm the baby,' " Humphries said. "It wasn't one of those, 'He's going to

(boss) you.' It's, 'You play beside me, you're older, I'm the young cat, teach me what you know.' "

Sometimes that's about being on the field, when the intensity is raised and the mind is racing and Mathis can help Humphries understand a certain play. Sometimes it's about what needs to be done in the meeting room, a place where Humphries acknowledged that sometimes last year he saw as a place to "kill time."

The maturity that Arians and Goodwin sought from Humphries was as much about the mental side of the game. That's why the “Knee Deep” nickname surfaced, for the pressure the coaches felt they needed to put on Humphries.

"(The nickname) was very frustrating at first," Humphries said. "But I kind of went from being angry about it to, 'OK, I'm going to use it as fuel. You call me Knee Deep but I'm going to show you why you drafted me in the first round so you don't need to do that anymore.' "

It has worked.

"I think he's a little bit more focused, he's matured a whole bunch – he's not all the way there yet – and I think he's night and day on the grass," Goodwin said. "I'm not worried about D.J. from a physicality standpoint or a knowledge standpoint. I just want to make sure he's prepared, and I think he'll be OK by the time the season starts."

Goodwin said Humphries is "not as goofy anymore" now that Mathis has arrived. It's the right path the Cardinals need both on as they move toward training camp and the regular season.

"I was kind of a slow developer myself," Mathis said. "It's a lot of pressure for a young guy who hasn't been in that role. There is a lot of uncertainty. But I expect a lot out of D.J."