Safety Tyrann Mathieu (32) and cornerback Patrick Peterson (21) are two key pieces back on defense

Cornerback Jerraud Powers hated to lose defensive coordinator Todd Bowles this offseason, but he was one brick. Defensive tackle Dan Williams and cornerback Antonio Cromartie were key starters who left in free agency, but they were two more bricks.

If a defense loses too many building blocks, the structure becomes wobbly, susceptible to disaster if a strong offense blows through.

The Cardinals' returning starters hear the whispers from those who believe replacing Bowles with a rookie defensive coordinator could topple them. This is met with a wry smile, as they heard it last year, too, when they had to replace linebackers Daryl Washington and Karlos Dansby and turned out fine.

Powers is adamant the rebar, the trenches and the concrete remain. The return to top form will take only a few cosmetic touches over the first few weeks of training camp.

"We've got our foundation, we've got our core of guys," Powers said. "We know how to pla

y Cardinals defense. I was talking to (cornerback Patrick Peterson) and them about it a few days ago. Three years ago, four years ago, when the record wasn't what it was, the defense was still a top-10 defense. I was like, 'It hasn't changed.' We've only gotten better as a defense.

"That's going to be the foundation of this team no matter how good our offense is. We're going to be built on our defense. We know in this division – what with the Rams defense, the Seattle defense, the 49ers defense – we've got to have a top defense to be able to win, and that's what we're going to do."

The transition from Bowles to James Bettcher should not be understated. Bowles, who left this offseason to take the Jets' head coaching job, was a master schemer, dialing up blitzes from all angles to keep offenses off-balance. He also knew how to leverage a player's strength and hide his weakness, using a variety of personnel in sub-packages depending on the offensive formation.

From all accounts, Bettcher has a bright mind, and the Cardinals don't plan on reinventing the wheel with him in charge. The defense is still expected to play plenty of man-to-man coverage and stay aggressive pressuring the quarterback. The skepticism is understandable until Bettcher proves his worth, but the players around him feel comfortable.

"Losing Bowles was tough because he's such a good coach, but that's the nature of the NFL," defensive end Calais Campbell said. "You replace players all the time, you bring new coaches in. Coach Bettcher is a great coach. Everybody has confidence in him. We're a very talented defense and the scheme's the same, so we don't have to really learn anything new. I think we'll pick up where we left off."

There is that saying in football, that Jimmys and Joes beat Xs and Os, and the talent on hand is why the Cardinals' defenders are so confident they can be successful.

The defensive line lost Williams and Darnell Dockett, but Frostee Rucker stepped i

n seamlessly last year, and the additions of Corey Peters, Cory Redding and Rodney Gunter should cushion the blow of the departures. Campbell is the lynchpin, fresh off his first Pro Bowl appearance and in the prime of his career.

"It was good for him to get to the Pro Bowl last year and be recognized as one of the premier guys in the league," coach Bruce Arians said. "I think it's helped his confidence."

The secondary is deep and versatile, and while it played pretty well last year, there are even higher hopes coming into 2015. Even though Cromartie is gone, Peterson and safety Tyrann Mathieu look primed to improve after injury-plagued seasons. Both possess the tantalizing physical skills to be game-changers.

"Obviously me and Pat have high expectations for ourselves, and we feel like we're a key to the team's success defensively," Mathieu said. "We definitely have to do our part – make turnovers and create some plays."

The pass rush and the depth at inside linebacker could be the biggest worries, although both were areas of concern last year and the Cardinals were able to hold opponents to 18.7 points per game, the fifth-fewest in the NFL.

Carson Palmer's health is the biggest key in the team's success, as a quarterback's worth trumps all other positions. When he started a game last season, the Cardinals went 6-0. Let's not forget, though, that the defense played a big role in that. It allowed only 15.6 points per game during those contests and scored three touchdowns.

There may be doubts as to whether the Cardinals can duplicate that productivity without Bowles. Powers has heard that before.

"We're going to have to find a way," Powers said. "I guess that's our identity of our team as a whole. You look at last year, all the injuries with Carson and everybody. Every week, it was, 'There's no way the Cardinals can do this or that,' and we always found a way. That's been our motto. We don't panic in whatever situation it is. Coach Bowles did a tremendous job as a D-coordinator here, and he deserved to get a head coaching opportunity, but now everybody thinks something's going to change with the defense. We'll find a way to still be a top-five defense and try to be the best defense in the league."