Arizona Cardinals free safety Tyrann Mathieu (32) celebrates his second interception of the game against the San Francisco 49ers during the first half of an NFL football game, Sunday, Sept. 27, 2015, in Glendale, Ariz. (AP Photo/Ross D. Franklin) Top Stories 0 Comments Share Former Cardinals kicker Phil Dawson retires Grace expects Greinke trade to have emotional impact Tyrann Mathieu is the only first-team All-Pro U25 defender in the league. He’s recovering from his second torn ACL, but his versatility is key to this defense. Mathieu had 31 defeats and 10 hurries in 2015. The other player pining for greatness already is running back David Johnson, who scored 13 touchdowns on limited touches as a rookie.As long as Mathieu is healthy, he is one of the most dominant under-25 players in the league.Johnson found his way to the field and ended up putting on a show for Arizona. In 125 attempts, Johnson ran for 581 yards and added eight rushing touchdowns. He caught four touchdowns on 36 receptions for 457 yards while also adding a kick return for a touchdown.Speedy receiver J.J. Nelson, nose tackle Rodney Gunter and linebacker Kareem Martin provide good depth. Tony Jefferson can play a traditional safety role and the Cardinals have moved Deone Bucannon into that “dollar linebacker” hybrid position, where he had 23 defeats last season.Bucannon led the team last year with 112 tackles. He added three sacks, three forced fumbles and one interception.Meanwhile, Nelson reeled in 11 receptions for 299 yards and two touchdowns. His longest catch was 64 yards and was the second-longest, only to John Brown, who had a 68-yard reception. The Arizona Cardinals and general manager Steve Keim have been very good at drafting quality players of late, and ESPN’s Scott Kacsmar’s ranking of the top under-25 talent in the NFL shows how those players stack up against the rest of the league.The ranking takes into account the number of snaps and games the players were a part of in 2015. It also uses positional value and a team’s ability to develop and retain young talent, among other things. Derrick Hall satisfied with D-backs’ buying and selling The 5: Takeaways from the Coyotes’ introduction of Alex Meruelo Then there are the Cardinals’ last two first-round picks. D.J. Humphries, a healthy scratch in all of 2015, should get his shot at right tackle this year. Robert Nkemdiche likely fell in the draft because of off-field concerns. We view him as a backup for 2016, but Nkemdiche could eventually develop into a force when lined up next to Calais Campbell.With Campbell’s age and play on the decline, it wouldn’t be surprising for Nkemdiche to be moved up into the starting lineup to help with locking down the line.He has already created a buzz in the Cardinals’ mini-camp before starting off training camp injured.