If you didn’t pay close attention to the Arizona Cardinals during the offseason, you’d think their defense was made up of two positions: inside linebacker and cornerback.

Those areas have been getting the most headlines since the 2013 season ended. Arizona lost both starting inside linebackers from a year ago when Karlos Dansby bolted to Cleveland in free agency and Daryl Washington was suspended for at least a year for violating the NFL’s substance abuse policy yet again. Later in the summer, cornerback Patrick Peterson became part of a national debate about who's the best cornerback in the league – him or Seattle’s Richard Sherman.

The Cardinals' Calais Campbell is looking to build on his nine-sack 2013 season. Christian Petersen/Getty Images

Entering training camp, however, there’s more to the Cardinals’ defense. Much more, in fact, and it may be the team’s best unit, potentially ever.

The defensive line, which anchored Arizona’s No. 1 run defense last season, returns in full plus a few additions. Defensive end Calais Campbell, nose tackle Dan Williams and defensive tackle Darnell Dockett will again be the starting front. Alameda Ta’amu, who split time with Williams last season, is expected to fully return from an ACL injury suffered in Week 17 last season. Arizona began stockpiling the future of the defensive line by drafting Kareem Martin and Ed Stinson, and while it'll be tough for them to crack the rotation early, Martin and Stinson will be learning from the some of best in the league. In 2013, the Cardinals allowed a league-best 84.4 rushing yards per game, and the 3.65 yards per run allowed were second lowest in the league.

Under defensive coordinator Todd Bowles, the Cardinals reacted to a change in scheme with open arms. He altered the gap system and allowed the Cardinals to play based on their skill instead of having their attacks plotted out. The result was 47 sacks, the sixth most in the league last season and the third most in franchise history. Campbell had a career-high nine sacks and linebacker John Abraham had a resurgence, tallying 11.5 sacks, which moved him into the top 10 on the all-time sack list.

Abraham was signed last July as a third-down rusher and spot linebacker. That all changed in Week 3 when the Cardinals lost Lorenzo Alexander, Sam Acho and Alex Okafor to season-ending injuries. But what role Abraham will have this season will be one of camp’s most intriguing questions because all three linebackers lost last year are returning healthy. Abraham, who was also selected for the Pro Bowl, has earned the start at outside linebacker but will be part of a competition that’ll include Alexander, Acho, Okafor and Matt Shaughnessy, who re-signed with Arizona during the offseason.

While there’s an abundance of options at outside linebacker, the opposite is the case at inside.

The Cardinals were left to start from scratch without Dansby or Washington. This much we know: second-year linebacker Kevin Minter will replace Dansby. Who’ll start next to him is anybody’s guess. Arizona’s options are limited. The Cards signed veteran Larry Foote and Ernie Sims to compete for the spot while another second-year linebacker, Kenny Demens, impressed during the offseason, giving him a leg up for the role.

Without set starters, rookies like Glenn Carson and Jonathan Brown, and fourth-year backer Keenan Clayton have an opportunity to earn playing time with impressive camps.

But without the core of the defense intact, added pressure will be put on the secondary. And this year’s defensive backfield may be as prepared as ever to handle it.

The addition of veteran cornerback Antonio Cromartie solidified Arizona’s corners as one of the best tandems in the NFL. Arizona replaced Yeremiah Bell by drafting Deone Bucannon at strong safety while Rashad Johnson will hold down free safety until Tyrann Mathieu returns from ACL and LCL surgery.

When all told – and when all healthy – the Cardinals may have one of the best overall secondaries in the league. During camp, Tony Jefferson will give Bucannon a run for the strong safety job while Johnson will try to prove that Arizona doesn’t need to wait for Mathieu to return.

Jerraud Powers, one of last year’s starters at cornerback, has been relegated to nickel back, and Bryan McCann, who’ll also compete for a gunner job, will be battling to be the next corner called upon.