Former Cardinals kicker Phil Dawson retires In four NFL seasons, Tyrann Mathieu has proven that when healthy, he is one of the league’s best defensive players.The problem has been, of course, keeping him healthy.Mathieu has yet to play a full season, and three of his four campaigns have ended with the former LSU Tiger on injured reserve.Heading into 2017 Mathieu is feeling healthy and confident, all while understanding that he still has plenty left to prove. The 5: Takeaways from the Coyotes’ introduction of Alex Meruelo Derrick Hall satisfied with D-backs’ buying and selling Mathieu is the second Cardinal to land on one of Schein’s lists, as he already named running back David Johnson as one of the most indispensable offensive players.The running back came in at No. 4.Johnson didn’t make this list in 2016. Now, having proven last season that he’s a bona fide star and one of the most well-rounded players in the entire league, Johnson earns a top-tier slot.Arizona can survive a Carson Palmer injury or a Carson Palmer skid, with Johnson dazzling and dominating like he does. Johnson posted 100 yards from scrimmage in each of the first 15 games of last season — an astounding NFL record. You could make the case that he’s the best runner and receiving target on the 2017 Cardinals. I know I would.In all, Johnson set a franchise record with 2,118 scrimmage yards, while his 20 touchdowns also topped the Cardinals’ record books as well as led the NFL in 2016. Top Stories Grace expects Greinke trade to have emotional impact 3 Comments Share Arizona Cardinals defensive back Tyrann Mathieu waits his turn to run drills during an NFL football organized team activity, Thursday, June 1, 2017, at the team training facility in Tempe, Ariz. (AP Photo/Ross D. Franklin) Again, no one doubts how good of a player he is, which is why last summer the Cardinals signed him to a contract extension even while he was recovering from a second torn ACL.When Mathieu is healthy and at his best, the Cardinals’ defense is one of the most difficult to handle, and it’s why even though they have other stars in cornerback Patrick Peterson and linebackers Markus Golden and Chandler Jones, NFL.com’s Adam Schein lists the Honey Badger as the league’s seventh-most indispensable defensive player.Mathieu hits and covers and breaks up passes. He changes games by creating turnovers. And most importantly, he is the heart and soul of this Cardinals team. With a banged-up Mathieu last year — the safety missed six games with a shoulder injury — the Cardinals missed the playoffs. There is a direct correlation. He’s that special.Mathieu is just such a crucial chess piece, with all the mismatch players and formations NFL offenses are rolling out these days. His skill set is extremely hard — if not impossible — to replace. And that, folks, is what we mean by indispensable.A defensive player of the year candidate before hurting his knee in Week 15 in 2015, Mathieu collected 36 total tackles with one sack and one interception in 2016 as he battled his knee and then a shoulder injury.