Cardinals' star defensive tackle Calais Campbell is one of the NFL's most prominent pending free agents.

The Cardinals made a Super Bowl push in 2016, kicking some salary cap money down the road to put the finishing touches on the roster.

The decision was certainly justified. After a 13-3 season and a berth in the NFC Championship game, the personnel seemed improved when outside linebacker Chandler Jones, guard Evan Mathis and safety Tyvon Branch were added to the fold.

But a season with such high expectations never went as planned. Special teams struggles, injuries, passing game ills and some bad luck contributed to a disappointing 7-8-1 record and no playoff appearance.

It was a critical swing-and-miss, and now, with both quarterback Carson Palmer and wide receiver Larry Fitzgerald in a year-to-year mode with retirement, this group could be down to one more title run.

Cardinals General Manager Steve Keim was in an enviable position last offseason, with almost every key piece already under contract and the ability to tinker with the roster. This offseason will be much more arduous. The Cardinals have 19 unrestricted free agents set to hit the market March 9, and because of some restructures in recent years, there are a lot of high-priced contracts on the books and relatively limited cap space.

It's going to make for some hard choices on key pieces like defensive tackle Calais Campbell, safety Tony Jefferson, tight end Jermaine Gresham and safety D.J. Swearinger.

"You can't have everybody back," Keim said during a recent appearance on Arizona Sports. "The way the salary cap is situated, you have to make some tough decisions. You have to make some tough decisions based on what the salary is, their age, their injury history. So many things go into it. That's the tough part of the business, because we all get emotionally attached to these guys."

According to salary cap website OverTheCap.com, the Cardinals currently have four players among the top-five salary cap hits at their position for 2017. Fitzgerald is second among wide receivers at $15.85 million; Palmer is third among quarterbacks at $24.13 million; Mike Iupati is third among guards at $9.7 million and Patrick Peterson is fifth among cornerbacks at $13.71 million.

That doesn't include Chandler Jones, who could be among the top-five outside linebackers if he plays the 2017 season on the franchise tag. The contracts aren't onerous, as all five have played at a Pro Bowl level during various stretches with the team, but it puts a lot of pressure on them to perform.

OverTheCap.com contributor Zack Moore said the Cardinals have a higher percentage of salary cap money tied into their top two contracts (Palmer and Fitzgerald) and their top three (add Peterson) than any team that has won a Super Bowl.

The Patriots, for instance, had their money more spread out this year, in large part because Tom Brady's cap hit was a comically low $13.76 million.

Avoiding many big money deals "is how (New England) built the 2016 team and something that the Cardinals will be unable to do, thus making them heavily reliant on those expensive players to provide them with an elite level of performance and then needing to fill the space in between with a lot of very low-cost players," Moore said.

The Cardinals do have a lot of proven performers still on rookie deals, including running back David Johnson, outside linebacker Markus Golden, left tackle D.J. Humphries, wide receiver John Brown, money linebacker Deone Bucannon and wide receiver J.J. Nelson.

That helps soften the blow if some of the free agents leave for more lucrative deals elsewhere. But there will still be a void to fill if a piece such as Campbell signs with another team, which Moore perceives as likely.

"They won't be able to replace his production with one player, but the hope when they drafted him in the first round had to have been that (Robert) Nkemdiche replaces Campbell in 2017, so he and others are going to have to step up to try to replace that production," Moore said. "The defensive line would be a good place for the Cardinals to look for a low-cost free agent."

Moore believes Jefferson may return, since a long-term deal would allow for a low 2017 cap hit. The Cardinals should have enough money to re-sign several of their lower-tier free agents if that's what Keim wants.

But there is a lot of cap space floating around the NFL, and the Cardinals have several prominent names hitting the market. Keim is staring down a critical offseason as he determines which players to chase hard, which ones to let walk and where to find valuable players at a discount.