It was the Arizona Cardinals offense that finished 2018 with a long list of lasts.

Yards, touchdowns, third-down conversions — the Cardinals weren’t good in many respects last season. Yet as the final month before the NFL Draft winds around a debate about quarterbacks Josh Rosen and potential No. 1 pick Kyler Murray, Arizona has and will continue to aggressively overhaul its defense.

According to ESPN’s Mike Clay, the Cardinals have the least returning on the defensive side of the ball compared to the other 31 NFL teams.

The players responsible for 95.2% of the Cowboys 2018 defensive snaps (including the playoffs) remain on the 2019 roster. That's highest in the NFL. The Cardinals currently sit last at 46.0%. pic.twitter.com/QRbngrI6SU

— Mike Clay (@MikeClayNFL) March 26, 2019

Such turnover for a middle-rung defensive squad from a year ago has meant Arizona general manager Steve Keim has been a busy man since the end of the 2018 campaign, before he fired head coach Steve Wilks.

In free agency and through the draft, expect that to continue as head coach Kliff Kingsbury and Keim allow new defensive coordinator Vance Joseph to mold the roster to fit his identity.

Key defensive players lost from 2018

Signed with other teams: Giants OLB Markus Golden (393 snaps), Buccaneers ILB Deone Bucannon (389), Giants DT Olsen Pierre (245)

Free agents yet to re-sign or sign elsewhere: S Tre Boston (950), DT Rodney Gunter (641), DE Benson Mayowa (550), LB Gerald Hodges (356), DE Zach Moore (245), CB Leonard Johnson (88)

Players the Cardinals released: Giants S Antoine Bethea (1,111), LB Josh Bynes (725), CB Bene Benwikere (560), CB Jamar Taylor (296)

The Cardinals released their top tackler, safety Antoine Bethea (121 tackles), from a year ago as well as their most consistent linebacker, Josh Bynes (75 tackles). The team frustratingly let go of two starting cornerbacks, Bene Benwikere and Jamar Taylor, in the middle of the 2018 season after each started multiple games for Arizona and fell out of favor.

Meanwhile, past over-achievers Markus Golden and Deone Bucannon saw their production dip in recent years due to injuries and scheme changes. They left as free agents.

Safety Tre Boston and tackle Rodney Gunter are among the top Cardinals free agents still on the market.

Key defensive players added

Defensive line: DT Darius Philon (Chargers)

Linebacker: ILB Jordan Hicks (Eagles), OLB Terrell Suggs (Ravens), OLB Brooks Reed (Falcons)

Defensive back: CB Robert Alford (Falcons), S D.J. Swearinger (Redskins), DB Josh Shaw (Buccaneers)

As Arizona transitions back to a 3-4 defense following a year in the 4-3, Hicks is the top of the free agency class added. He signed a four-year deal worth $36 million, a value bargain compared to the other top linebackers who were free agents this offseason.

But before free agency began, Keim attacked positions of need, signing Alford on a long-term deal to play alongside Patrick Peterson and adding Swearinger before the end of 2018. Suggs and Reed bring experience and a local taste to the outside linebacker spot on the other side of Pro Bowler Chandler Jones.

Key returning defenders

Defensive line: DT Corey Peters (734 snaps), DT Robert Nkemdiche** (426), DT Vincent Valentine (43), DE Cameron Malveaux (42)

Linebacker: OLB Chandler Jones (968), ILB Haason Reddick (846), OLB Vontarrius Dora (67), ILB Zeke Turner (18)

Defensive back: CB Patrick Peterson (1,106), DB Budda Baker (938), DB David Amerson (293), CB Brandon Williams (85), S Rudy Ford (62)

The core players remain. Already, Jones and Peterson have their complementary pieces at their positions. Yet depth remains an issue, as do question-marks around Reddick and the inside linebacker depth after Hicks.

Along the defensive line, Philon could be a low-key big addition. But with Robert Nkemdiche recovering from ACL surgery this offseason, there room for improvement with the remaining free agents or perhaps the draft, where a deep class of defensive linemen could be an option with the No. 1 selection or beyond.

Follow @kzimmermanaz