The Raiders announced the deal with Roach, who is the second linebacker signed by the team this week, following a three-year, $6 million deal given to Kaluka Maiava on Wednesday.

Maiava is expected to replace Philip Wheeler, who left to sign a five-year, $26 million deal with Miami earlier this week. The deal with Roach fills the hole in the middle created by McClain’s disappointing play.

“It just seemed like Oakland was an opportunity that was too good to pass up,” Roach said.

McClain, the eighth overall pick in the 2010 draft, has been mostly a disappointment in Oakland. He struggled during his first two years and then clashed with coach Dennis Allen and his staff last season. McClain had his role significantly reduced last season and then was suspended for two games for conduct detrimental to the team.

He did not play after the suspension, playing the role of a scout team running back in practice instead. McClain is not expected back next season. Omar Gaither stepped in for McClain last year but is currently a free agent.

Roach, a former undrafted free agent out of Northwestern, spent the past six seasons with the Bears playing alongside stars Brian Urlacher and Lance Briggs.

“It’s been great,” he said. “Those guys are friends of mine and more importantly they are great examples of how to be a pro and how to be successful at the highest level. Just being behind them and next to them the last few years has really helped.”

Roach played 80 games over that span and started 59, including 29 the past two years. He had 65 tackles, 1½ sacks, four passes defensed, 1 forced fumble and one fumble recovery last season.

Roach has mostly played strong side linebacker during his six seasons with the Bears, but has also seen time in the middle. He played the final four games there last season with Urlacher sidelined by a hamstring injury, making 31 tackles, including three behind the line.

“That was huge,” Roach said. “You don’t really know yourself if you can do something until you have a chance to do it. It was big for being able to get the film out there and show my versatility.”

Most of Oakland’s work so far this free agent season has been on upgrading a defense that gave up the fifth most points in the NFL last season. There are only four returning starters on the roster with defensive tackle Tommy Kelly expected to be let go later this offseason.

General manager Reggie McKenzie already cut defensive back Michael Huff. Defensive linemen Desmond Bryant and Matt Shaughnessy and Wheeler have left already as free agents.

Along with the two new linebackers, McKenzie has also signed a pair of defensive linemen in tackle Pat Sims and end Jason Hunter.