ALAMEDA – The Raiders added competition to their secondary during the NFL Draft. Defensive backs were taken early to strengthen an area of weakness, where depth and talent was required.

Enter cornerback Gareon Conley in the first round, safety Obi Melifonwu in the second. While last year’s starting lineup remains intact, the Raiders have worked both rookies into the first-team sub package.

That was the case on Tuesday, with Conley working as a slot cornerback and Melifonwu filling a hybrid linebacker/safety role.

Defensive coordinator Ken Norton Jr. believes those two have the traits required to make an impact.

“(They have) a lot of speed, youth, length all the things you like to get on matchups,” Norton said after Tuesday’s OTA session. “You really need matchups. These guys do a great job disrupting and they should cover really well.”

The Raiders need help on passing downs, especially when opponents send volume into the pattern. They’ve struggled covering tight ends and running backs, and making sure receivers don’t get open deep.

The linebacker corps is thin and inexperienced, and the Raiders seem willing to try different cover men in those packages. That might mean an extra safety.

“You can always do a multitude of things,” assistant head coach – defense John Pagano said. “From talking to Kenny about the different type of personnel groupings that you can find yourself in. I think you always have to find a way in this league to make sure you have to have a great understanding of getting the best 11 out there on the field at all times. Situational football is the key, and being situational masters, that’s one thing that we always have to take our level to higher level as coaches so they understand the game even easier.”

Conley and Melifonwu having been working hard during these OTAs. They have first-unit responsibilities in the sub package, with Conley as a second-team slot corner and Melifonwu as a second-team strong safety.

“They love practicing. They chase well,” Norton said. “They’re always trying to improve and they’ve done a great job of understanding our system, understanding what we’re trying to teach them. They’re very good learners.”

Here are a few more observations from Tuesday’s OTA session:

-- Running back Marshawn Lynch didn’t participate in team drills on Tuesday, a day after Jack Del Rio tweeted out practice film of him doing exactly that. He was active in individual drills and install periods.

-- The defensive coaching staff is not worried about third-round defensive tackle Eddie Vanderdoes missing the offseason program while UCLA’s academic year wraps.

-- Right tackle Marshall Newhouse missed Tuesday’s work for an undisclosed reason. Vadal Alexander and David Sharpe took first team reps in his place.

-- Veteran offensive lineman Austin Howard suited up for Tuesday’s practice but did not return to action in team drills or intense individual work.

-- Guard/center Jon Feliciano appeared to injury his knee midway through practice, but tried to walk it off after being down an extended stretch with teammates around him. He did not return to practice, but was moving under his own power. His injury wasn’t addressed by the team.

-- Cory James and Tyrell Adams remain the team’s first-unit inside linebackers. Marquel Lee and Jelani Jenkins ran there with the second team.

-- Defensive linemen Denico Autry and Fadol Brown were not present during this voluntary OTA session for undisclosed reasons.