The Cardinals' defense is getting it done but bigger tests loom

The Arizona Cardinals are the NFL's last undefeated team. Their headline attraction thus far has been quarterback Kyler Murray, who's already being mentioned as a possible MVP candidate. But the Cardinals' defense also deserves plenty of credit and bears watching as the season progresses.

Arizona has limited three of its four opponents to 20 points or less. The Tennessee Titans were one of them, despite entering the campaign with what might be the league's best all-around collection of skill players. The Los Angeles Rams were another. Their whizbang offense with Matthew Stafford now at the controls seemed unstoppable until the Cardinals shut them down last Sunday.

Of course, there's a long ways to go, but there's a lot to like about Arizona's D. Heading into Week 5, the Cardinals rank sixth in defensive DVOA and third in DVOA against the pass even though they've played the league's 12th-hardest schedule of offenses. The team's nine takeaways are the third-most in the NFL, and slot cornerback Byron Murphy Jr.'s three interceptions are tied for second-most.

The Cardinals began the season with a bang by sacking Titans quarterback Ryan Tannehill six times and hitting him on nine occasions. Veteran edge rusher Chandler Jones accounted for five sacks and six hits in that game. Even though the unit hasn't produced another performance quite so dominant, it has cooked up consistent pressure while also getting steady coverage from a cornerback group that came into the season as a potential weak spot.

Defensive coordinator Vance Joseph schemed up a fair number of blitzes as Arizona has brought more than four pass-rushers 53 times - tied for sixth-most in the league, per PFF. But last week against the Rams, the Cardinals' blitz rate was just 18.6% - far and away their lowest total of the season. It was enough, though.

Arizona baited Stafford into throwing an early interception and forced a fumble to create a short field. Both turnovers led to touchdowns. The Cardinals also got a fourth-down stop that resulted in a missed field goal and stopped L.A. on downs at the 1-yard line.

Like any good defense, Arizona has benefited from contributions from numerous players, as USA Today's Doug Farrar explains. The fulcrum is linebacker Isaiah Simmons, the eighth overall pick in the 2020 draft. Simmons has grown into his role as a multi-dimensional player capable of spying, rushing the passer, or working in coverage. Just look at how he's being used:

He's the definition of an every-down defender, a do-it-all hybrid whose play-anywhere skills are increasingly in demand in today's pass-heavy game.

Simmons played a similarly versatile role last season, but he was still getting his sea legs as a rookie. A lack of offseason practices due to the pandemic hindered his development, so he played only 34% of the defense's snaps in 2020. Simmons rarely leaves the field this year, playing nearly 90% of the time.

The Cardinals' pass rush has produced a pressure rate of 35.8%, which is 11th-best in the league, according to PFF. Adding veteran J.J. Watt has helped in this regard. Unlike his years with the Houston Texans, when he mostly played on the left edge, Watt has lined up all over the defensive line in Arizona. He's doing most of his work on the interior, where his five hits tie the league lead, his 12 hurries rank third, and his pass-rush productivity of 6.8% is fourth, per PFF.

The success of the defense's back end has been the biggest surprise for the Cardinals. The team signed veteran Malcolm Butler in free agency to replace longtime stalwart Patrick Peterson, who left for the Minnesota Vikings. But then Butler retired for personal reasons just before the regular season was about to start. That thrust rookie fourth-round pick Marco Wilson into a starting role alongside Murphy and 32-year-old Robert Alford, who Arizona released and then re-signed during the offseason. It's all worked out.

Murphy, a 2019 second-round pick who showed modest improvement after struggling mightily as a rookie, has particularly made enormous strides this season. He has those three picks, including one on a deep ball from Stafford to DeSean Jackson while playing on the outside. The other two interceptions came in Week 3 against the Jacksonville Jaguars, with one of those being a pick-6. The first interception over Jacksonville happened because linebacker Jordan Hicks knocked the ball from Jacob Hollister's hands. Hicks has also played nearly every snap (98%) this season.

Murphy had the task of primarily sticking with the Rams' ever-dangerous slot receiver Cooper Kupp, who came in with five TDs and averaged eight catches and 122 yards per game to start the campaign. Kupp produced just five catches (on 13 targets) for 64 yards against the Cardinals. When Murphy shadowed him, Kupp was targeted five times and had only two catches for 44 yards, per PFF. Though Kupp came in averaging 58.6 yards after the catch, he compiled just 17 against Arizona.

The Cardinals are also getting solid play from Budda Baker and Jalen Thompson, who can be interchangeable parts as free and box safeties. But it's Thompson, in particular, who's become a chess piece for Joseph. He's played 137 snaps as a free safety, 70 in the box, 30 as a slot corner, and nine as a wide corner, per PFF. Arizona selected Thompson in the fifth round of the 2019 NFL Supplemental Draft. He missed most of last season with an ankle injury.

The Cardinals' D has benefited from some luck by recovering five fumbles, tied for the league-high. Stafford also misfired a handful of open throws last week, and Rams head coach Sean McVay did Arizona some favors by settling for field goals when the math suggested it might have been better to go for it. Murray and Arizona's offense capitalized by boat-racing L.A. with four touchdowns and three field goals on its first nine possessions. That's something good teams do.

Arizona's defense has a bit of a bend-but-don't-break quality to it. Opposing offenses have a success rate - defined by Ben Baldwin's database as plays with a positive expected points added value - of 51.5%, which is the fourth-highest in the league. And the dropback success rate for the Cardinals' defense is 53.3%, which ranks 25th. Despite that, the defense overall has an EPA per play of minus-0.078, which is fifth-best.

Things can still go sideways. The schedule will get tougher, with games against the Cleveland Browns, Green Bay Packers, Carolina Panthers, and Dallas Cowboys. Arizona also still has to go through the gauntlet of five remaining matchups versus the rest of the NFC West, the NFL's best division. On Sunday, the Cardinals will take on Trey Lance in his first career start.

Arizona stumbled to an 8-8 finish last year after getting off to a 6-3 start, with Kliff Kingsbury's inability to scheme around Murray's shoulder injury and the ailment itself largely to blame. Nearly a quarter of the way into 2021, the team's defense is holding up its end of the bargain.

Dom Cosentino is a senior features writer at theScore.