Cardinals cornerback Patrick Peterson gives tips to rookie cornerback Brandon Williams during an OTA.

Tyrann Mathieu was an all-pro last season, a first-time Pro Bowler and in the discussion for defensive player of the year.

But the safety chuckles when talking about competing with departed veteran Rashad Johnson for playing time.

"He knew everything," Mathieu said. "For me, I was always a step behind."

The Cardinals' self-titled "No Fly Zone" had roster changes this offseason. Both Johnson and veteran cornerback Jerraud Powers left, to the Titans and Ravens, respectively. The team was looking to get more athletic and faster in the secondary,

and chose to move on.

Yet there is little question the Cards benefitted from the knowledge and leadership from the two, a role that now mostly falls on the team's two star defensive backs: Mathieu and cornerback Patrick Peterson, himself an all-pro.

"I think myself and Pat, we became more vocal last year," Mathieu said. "We could never really replace Rashad. He called out 100 percent of the plays, but I can call out 70 percent of them, so, as time goes on, hopefully I can call out 100 percent.

"Patrick and I are perfect for the role, we've been embracing it since last year and even this spring. Not being on the field (after surgeries), we've been able to see it from a different perspective. We lost some great talent and some great leaders, but I am real excited about some of these young guys we got."

It isn't so much the lost leadership that gives Peterson pause – like Mathieu, he feels like both have already had that role – as much as lost chemistry.

At one point this offseason, Peterson and some teammates were watching video of a game against the Rams from last season. Peterson watched the Cardinals run a coverage they hadn't worked on in practice but that they still were able to

execute, with Peterson and Powers switching assignments on the fly.

"That's where the veteran comes out of the guys, playing together for so long," Peterson said. "Now, it is different."

Peterson called it "weird" that Johnson and Powers were no longer around. Johnson had served as a big brother to Peterson when Peterson arrived in the league, and Powers came in at the same time as Mathieu in 2013.

Some teammates have teased Peterson that he's an "old man" given his experience, even if he is just 25. He and the 23-year-old Mathieu have experienced players like Justin Bethel and Tony Jefferson around, but mostly it is youth and inexperience sharing the meeting room.

"I am taking the initiative to learn everything, to understand what the coaches want from us as a defense and from me as an individual, for me to understand what the defensive line is doing, and the linebackers and the secondary," Mathieu said. "I just want to have that overall knowledge of what's going on on defense. That way, I can be able to help everyone out, not just the secondary."

That's how Johnson operated and how Powers helped.

"Those guys were great leaders but we have great leaders all over the defense, in their own way," Peterson said. "That chemistry will be different. We're building it, but it's something totally different than years past."