Resources are finite in the NFL, which is why the Cardinals let star defensive tackle Calais Campbell walk in free agency last season.

He signed a lucrative deal with the Jaguars and had a fantastic year, finishing tied for second in the NFL in sacks with 14½. While there's no question the Cardinals would have preferred to keep him, the defensive line ended up acquitting itself pretty well.

The Cardinals allowed only 3.5 yards per carry in 2017, which was the third-best mark in the NFL. The line didn't put up big sack numbers, but as the year went on it seemed like the interior pressure on opposing quarterbacks intensified.

Olsen Pierre was the breakout player, compiling 5½ sacks, while Corey Peters had an underrated season and Josh Mauro and Frostee Rucker were again solid.

Robert Nkemdiche saved his two best games for Weeks 16 and 17, and that is something to be encouraged about moving forward. The former first-round pick had a fumble recovery for a touchdown against the Giants, and then posted an 82.5 Pro Football Focus grade against the Seahawks.

The Cardinals have plenty of concerns this offseason. The big decisions, of course, are head coach and quarterback, while wide receiver and offensive line are two other areas that could also get scrutinized.

General Manager Steve Keim may choose to add to the defensive line, but it doesn't seem like a glaring hole. Peters signed an extension during the season, while Nkemdiche, Mauro and Rodney Gunter are under contract. Pierre is an exclusive rights free agent, and the team will assuredly re-sign him.

Rucker is an unrestricted free agent and Xavier Williams is a restricted free agent, but neither would break the bank if the team brings them back.

Campbell played like a star in 2017, but was also paid like one. The defensive line proved capable without him at a bargain price, and those same pieces will allow Keim to allocate his cap money elsewhere this offseason if he so chooses.