Raiders defensive coordinator Paul Guenther is competitive. His 2018 roster was not.

Oakland Raiders defensive coordinator Paul Guenther on the sideline during the second half of their NFL game against the Denver Broncos in Denver, Colo., Sunday, Sept. 16, 2018. Heidi Fang Las Vegas Review-Journal @HeidiFang

Oakland Raiders defensive coordinator Paul Guenther at the team's NFL training camp in Napa, Calif., Sunday, July 29, 2018. Heidi Fang Las Vegas Review-Journal @HeidiFang

ALAMEDA, Calif. — Raiders defensive coordinator Paul Guenther is competitive.

His 2018 roster was not.

Five of 11 starters in Week 1 — defensive end Frostee Rucker, linebacker Derrick Johnson, safety Reggie Nelson, safety Marcus Gilchrist and cornerback Leon Hall — are currently out of the league. Two others, cornerback Rashaan Melvin and defensive end Bruce Irvin, are on other rosters.

Guenther hoped All-Pro defensive end Khalil Mack wouldn’t leave the field; he never arrived to the building. He hoped rookie defensive end Arden Key could be a situational pass rusher; he averaged more than 40 snaps per game.

It proved difficult to run a new system without a pass rush or team speed.

“By far, my hardest year of coaching,” Guenther said Tuesday.

A new season gradually approaches for the second-year coordinator. Here in June, reasons abound as to why his defense is headed in the right direction. Given the roster’s youth, however, the defense must work to dispel the external belief it’s at least another year from gaining true form.

Lamarcus Joyner is one positive.

The former Los Angeles Rams defensive back was the defense’s prized veteran addition this offseason, signing a four-year, $42 million contract in March. Although he worked mainly at safety the past two seasons, Joyner is reprising his role as a primary nickel cornerback here.

He offers vocal leadership, someone with a strong understanding of not just coverage concepts but run fits and blitzing.

“He’s a perfect fit for me for the nickel spot,” Guenther said.

At defensive end, the Raiders signed such veterans as Josh Mauro and Benson Mayowa. Between them and No. 4 overall pick Clelin Ferrell, Key should be freed up to revert to the situational pass-rush role the Raiders originally envisioned when drafting him in the 2018 third round.

Key is one piece to a greater youthful puzzle.

Defensive tackles P.J. Hall and Mo Hurst Jr. are entering their second NFL season, too. Ferrell, fourth-round pick Maxx Crosby and seventh-round choice Quinton Bell are rookie defensive ends. Defensive tackle Eddie Vanderdoes, a 2017 third-round pick, is competing for a role and roster spot after an ACL tear sidelined him throughout last season.

Rookie safety Johnathan Abram, the No. 27 overall pick, has impressed.

He began organized team activities with the second-team unit, but on Tuesday, he worked with the starters opposite Karl Joseph. Guenther anticipates “tighter coverage” in the secondary, he said.

To what degree the pass rush improves remains to be seen.

The Raiders were the only NFL defense to record fewer than 30 sacks in 2018. They had 13, fewest in franchise history, while allowing a league-high 467 points.

“It’s something that you don’t always want to go through, having a rough year like we did,” Guenther said. “But obviously, you start to learn how to build these things. How to build your lineup card and what it should look like and how you envisioned it. That was the positive for me. I always tell the players, if you don’t learn from failure, you’re making a mistake. You have to learn from what we did good and what we did bad and build off of that in the future.”

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Contact reporter Michael Gehlken at mgehlken@reviewjournal.com. Follow @GehlkenNFL on Twitter.