At first glance, many rank the secondary of the Arizona Cardinals as one of the best in the league, and comparable to that of the Denver Broncos, whose defensive backs were arguably the key to stopping the Cowboys running game to an extent that we hadn’t seen around these parts in a very long while. Cornerback Patrick Peterson and safety/cornerback Tyrann Mathieu are certainly two of the best in the league at their positions, and they will make things very difficult for Dak Prescott and the Cowboys receivers on Monday night, but what the Cardinals don’t have that the Broncos do is depth in their secondary.
On top of arguably the two best cornerbacks in the league in Aqib Talib and Chris Harris Jr., the latter of whom can apparently double as a safety in spot duty, the Broncos also have an elite third corner in Bradley Roby and an excellent safety in Darian Stewart. The Cardinals do not have that luxury.
Last season the Cardinals had a top-five pass defense, but gone from that unit are both safeties in Tony Jefferson, now with the Ravens, and D.J. Swearinger, now with the Redskins, as well as cornerback Marcus Cooper. Both Cooper and Swearinger played over 75% of the snaps last season while Jefferson played 86%, and the three accounted for seven interceptions, 24 pass deflections, and four sacks. The only defensive back to play more snaps last year for the Cardinals than those three was Peterson, although the fact that Mathieu missed a handful of games certainly plays into that.
Even so, the fact remains that Arizona is now without three of their top five defensive backs from last year, which is a significant blow for what is supposedly one of the best units in the league. They have been replaced by cornerback Justin Bethel, who now starts after only playing about 25% of the snaps last season, and two veteran safeties who have seen better days in Tyvon Branch and Antoine Bethea.
Long story short, despite the two big names at the top of the depth chart, there are gaps in this secondary that the Cowboys can exploit that did not exist in the Broncos secondary. For that very reason the Cowboys must hone in on where the ultra-versatile Mathieu lines up. Everybody knows where Peterson will be, shadowing Dez Bryant, most often on the boundary. It won’t take too much to identify where he is and attempt to take advantage of it when possible.
But Mathieu is a different case altogether, he’s listed as a safety but given the multiple defense Arizona employs he can line up at outside corner, in the slot, attack on blitzes, or play a more traditional role as a deep centerfield safety. In his breakout 2015 season he had an astounding 11 TFL to go along with five interceptions and 17 pass deflections, impacting the game both at the line of scrimmage with his ability to blitz and tackle, and on the back end with his range, speed, and ball skills.
You never know exactly how he will be used but I suspect that the Cardinals will look to have him primarily hone in on intermediate targets Cole Beasley and Jason Witten, but given the relative mediocrity of the rest of the secondary, it’s possible that they use him interchangeably as the game goes on to address whatever problem areas come up, whether that is Beasley or Witten, Ezekiel Elliott out of the backfield, or something else.
Dak Prescott and the Cowboys cannot let Arizona use Mathieu’s versatility to cover up for average at best players in Bethel, Branch, Bethea, etc. They must be able to quickly identify how he’s being utilized and then use that to attack other areas of the defense. No matter how good Peterson and Mathieu are they’re only two players, unlike the Broncos four, and they can’t be everywhere on the back end. Peterson will be doing his thing on Bryant, that’s a toss-up that could go either way on any given play, but being able to quickly locate Mathieu will allow Prescott to adjust and find matchups to exploit on the fly.
Conversely, if the Cowboys are unable to locate him it could lead to a huge play in the opposite direction. The Cardinals have a very good pass rush behind outside linebackers Chandler Jones and Markus Golden, and of course they’ll be playing at home with the crowd behind them in a primetime game. If that pass rush can get cranked up on third and long and Prescott isn’t careful, or is unable to figure what exactly Mathieu is doing, the young quarterback could easily be fooled into a big mistake that leads to a critical turnover. Given the Cardinals below average offense it will likely take at least a turnover or two from the defense for them to win the game, and there is nobody more likely to give that to them than Mathieu.