Jon Gruden targeted Paul Guenther as his defensive coordinator in his return to Oakland even before he got the Raiders job Youth New England Patriots Jerseys , believing his aggressive defensive scheme was just what the team needed to reverse years of bad play.

Guenther's task has been even harder than originally thought because he is still waiting to get Oakland's best defensive player in camp.

Star edge rusher Khalil Mack skipped the entire offseason program and now extended his holdout into training camp as he seeks a long-term contract commensurate with the skills of one of the NFL's top defensive players.

"I really can't worry about that right now," Guenther said Sunday after Oakland's first padded practice. "I'm just trying to coach the guys who are out here. Obviously when he gets here, if he gets here, he'll be an exciting piece to add."

There is no indication of when that time will come as Mack's camp and Raiders general manager Reggie McKenzie have been quiet about negotiations. Mack is entering the final season of his rookie contract that is set to pay him $13.8 million and Oakland would have the option of using the franchise tag next offseason if no long-term deal is reached.

Mack is one of several prominent holdouts this summer Cheap Albert Wilson Jersey , joining players like Rams defensive tackle Aaron Donald, Seattle safety Earl Thomas. Pittsburgh running back Le'Veon Bell is also staying away from training camp but is not a holdout since he has not signed his franchise tender.

"He's working," fellow edge rusher Bruce Irvin said. "I talk to him every day. He misses it. You just know how it is. He's working his butt off and when he gets in here he'll be ready."

Mack has been one of the top defensive players in football since being drafted in the first round in 2014. He was a first-team All-Pro at both defensive end and linebacker in 2015 and won AP Defensive Player of the Year in 2016. He has 40 1/2 sacks in four seasons and leads the NFL in QB pressures with 185 1/2 since entering the league, according to SportRadar.

Free-agent acquisition Tank Carradine has taken over Mack's role at defensive end on the base defense but is not an accomplished pass rusher. The Raiders hoped to upgrade that rush by drafting defensive end Arden Key and tackles Maurice Hurst and P.J. Hall.

Key and Hurst have shown good bursts early in training camp as the Raiders prepare without Mack.

"We can't worry about who isn't here because when Khalil gets tired Josh Rosen Youth Jersey , when he goes out of the game, the guys who are here have to go into the game and play while he is tired," Irvin said. "He rarely gets tired, but when he does those guys have to be ready. We're focused on getting these young guys ready and that stuff will take care of itself."

Irvin is also taking on a bigger role in the pass rush after spending his first two seasons in Oakland as an outside linebacker who also rushed the passer.

Irvin dropped into coverage on almost one-third of pass plays last season Buccaneers Cheap Jerseys , according to SportRadar. But Guenther plans to use him almost exclusively as a defensive end in his defense.

"I just think his best gift is going forward," Guenther said. "That's what he should be doing each and every down. Instead of playing linebacker and dropping into coverage, we have to utilize his and everybody else's talents the best we can."

NOTES: CB Gareon Conley has missed the past two days with a hip strain sustained on the first day of practice. ... RB Jalen Richard left practice with an undisclosed injury.

The Buffalo Bills have signed free agent linebacker Keenan Robinson in filling out their 90-player roster two days before opening training camp.

Robinson signed on Tuesday and has five seasons of NFL experience, including the past two with the New York Giants. He was limited to playing six games last year before sustaining a season-ending quadriceps injury.

Robinson spent his first four seasons with Washington after being selected in the fourth round of the 2012 draft. He missed all of 2013 with a torn pectoral muscle.

Overall Youth Buffalo Bills Jerseys , he has two interceptions and 1 1/2 sacks in 58 career games, including 30 starts.

The Bills open training camp in suburban Rochester on Thursday.

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