"I've known Derrick a while -- he brings us status at a critical position," Gruden said following Oakland's first day of rookie minicamp. "He's got a great history in this league, been productive under a lot of different coaches, different schemes. He understands the AFC West. He certainly understands this rivalry. I'm really excited to add him to our team, to Tahir Whitehead and some of our young linebackers. I think his presence will be very valuable."
The Raiders, though, will have to make another roster move to make the Johnson signing official. The team waived linebacker Cory James due to a failed physical and defensive end Armonty Bryant with a non-football illness and signed six undrafted rookie free agents on Friday, meaning its offseason roster is at the maximum 90 players.
"We've made a lot of moves and that probably means we're going to make more moves in the coming days," Gruden said. "We just want to get better. There's a strong sense of urgency to get better.
"Getting a guy like Derrick Johnson, I think, could be huge for us."
And while the pending signing of Johnson would seem to close the door on NaVorro Bowman returning to Oakland, Gruden said he would not eliminate that possibility.
The Chiefs announced on Feb. 13 that they would not re-sign Johnson, who spent 13 seasons with the team. Johnson said in a statement that he plans "on playing for several more years."
Raiders fans will remember Johnson as the player who ended running back Darren McFadden's MVP-caliber 2011 season with a clean tackle that injured McFadden's foot. The Raiders were 4-2 at the time and finished 8-8.
Johnson, who turns 36 on Nov. 22, was the Chiefs' first-round draft pick in 2005 out of Texas, No. 15 overall. He was the longest-tenured Chiefs player along with punter Dustin Colquitt, who arrived in the same draft two rounds later.
Johnson stayed with the Chiefs through five head coaches and four general managers. He was a steady presence at inside linebacker, equally adept at defending the run and the pass. He was selected to play in the Pro Bowl four times and was a first-team All-Pro in 2011.
He twice returned from a torn Achilles tendon -- suffering season-ending injuries in the 2014 opener and again late in the 2016 season.
The move was first reported by NFL Network.