Paul Guenther is installing a new defense for the Oakland Raiders with the most important part of the unit missing.

Star pass rusher Khalil Mack remains away from the Raiders in a contract dispute this offseason while Guenther works on rebuilding a defense that has been one of the league's worst for more than a decade.

"He's going to have a lot of catching up to do Bears Joel Iyiegbuniwe Jersey ," Guenther said Tuesday.

"We're going to have to have a plan for that for sure. I'm really concerned about the guys that are here now working. These guys have been busting their tails every day. Coming in early. Meeting with the coaches. Being great in the meeting rooms. Communicating on the field."

Mack, the 2016 AP Defensive Player of the Year, is entering the last year of his rookie contract that pays him $13.85 million this year and is seeking a long-term deal that will make him one of the most highly compensated non-quarterbacks in the NFL.

Mack has missed the entire voluntary portion of the offseason and has not indicated whether he plans to report for next week's mandatory minicamp or risk fines of more than $80,000.

Guenther's focus now is on the defenders who are at practice this offseason.

"I'm trying to get the guys that are here better," he said. "These guys have been busting their tails, trying to get better. Trying to make the team. There's some guys out there that I really think have a lot of uncovered ability.

"We're trying to get it out of them to understand, 'Hey Hayden Hurst Ravens Jersey , you might not be a 60-snap-a-game guy. You might be a 15 snap-per-game guy, do the best job in your role and how you can help us win.'"

Guenther was one of Jon Gruden's first hires after being brought back for a second stint as coach in Oakland back in January and immediately given a tough task.

The Raiders defense has consistently been one of the league's worst the past 15 years under coordinators Chuck Bresnahan, Rob Ryan, John Marshall, Jason Tarver, Ken Norton Jr. and John Pagano.

Oakland ranks last in the NFL in takeaways and points allowed in that span, second worst in yards allowed per game and third worst in sacks as the unit has struggled consistently from the front seven to the secondary.

Guenther's defenses in Cincinnati have been some of the best in the league during his time as coordinator there.

"Paul Guenther's defense Josh Jackson Jersey Youth , it's very aggressive," new middle linebacker Derrick Johnson said.

"So many different looks. The onus is really on the linebackers to learn a lot of stuff. That's good for myself because I know a lot. It's putting a lot of pressure on me to learn it quickly.

"Learn it well enough where I can put my own flavor in making plays on this defense. I'm having fun with it now. The last couple of days have been my best days, running around. ... Once you can get it down really well, you'll look a lot faster out there on the field. We all can run fast and jump high, but mentally, once you got it down, all your abilities Luke Falk Jersey Elite , your talents can show out there on the field. That's what we're doing right now. We're not there yet, but we're getting there."

Last year was particularly bad when the Raiders became the first team to fail to intercept a pass for the first 10 games of the season and had just 14 takeaways all season.

To change that, the Raiders have made significant changes in personnel this offseason, bringing in Johnson to anchor the middle of the defense along with new linebackers Tahir Whitehead and Emmanuel Lamur; drafted Maurice Hurst, P.J. Hall and Arden Key to boost the pass rush; and signed defensive backs Rashaan Melvin, Daryl Worley, Marcus Gilchrist and Leon Hall.

Oakland is also hoping to get a boost with healthy seasons from last year's top two picks Authentic Anibal Sanchez Jersey , cornerback Gareon Conley and safety Obi Melifonwu, who were limited to 127 defensive snaps as rookies because of injuries.

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