Oakland hired Bresnahan last month as a defensive assistant, but did not immediately specify his duties. Coach Hue Jackson said he had talked to some people outside the organization about the job, but stuck with a coach he had worked with before in Cincinnati.
"The fact that I've had the chance to be in defensive meetings with Chuck and watch him lead the defensive staff made it an easy decision to name him our defensive coordinator," Jackson said in a statement. "I am impressed with his passion, attention to detail and energy. This staff gives us the opportunity to have one of the top defenses in the NFL."
The Raiders have made significant changes on their defensive staff since Jackson replaced Tom Cable as head coach in January. Hall of Famer Rod Woodson was brought on to coach the cornerbacks and Greg Biekert was promoted to linebackers coach.
Both Woodson and Biekert played for Bresnahan during his stint as defensive coordinator of the Raiders from 2000-03. Oakland won the AFC West in his first three seasons and went to the Super Bowl following his third year in 2002.
"This is an incredible opportunity for me to come back to the Raiders and work again where we had so many great years," said Bresnahan, who was also a defensive backs coach in Oakland in 1998-99. "It's so exciting to be reunited with Hue Jackson because of the passion and energy that he brings. I'm also thrilled to be a part of this talented staff, many of whom I've shared previous success with."
The Raiders have been aggressive so far this offseason about keeping some of their key potential free agents on the defensive side of the ball.
Oakland gave cornerback Stanford Routt a three-year, $31.5 million deal, signed defensive tackle Richard Seymour to a $30 million, two-year contract, placed an $11,312,000 franchise tag on linebacker Kamerion Wimbley that has already been signed, and agreed to an $8 million, two-year contract with defensive tackle John Henderson.
Oakland has two other key defensive free agents in Pro Bowl cornerback Nnamdi Asomugha and safety Michael Huff. Decisions on those two players won't be made until after a new collective bargaining agreement is reached.
Regardless of what happens with Asomugha and Huff, the Raiders have some talented, young defenders whom they believe can be part of a stellar defense.
Oakland's top two draft picks from last year, middle linebacker Rolando McClain and defensive end Lamarr Houston started right away as rookies and showed promise.
Defensive tackle Tommy Kelly had his best season with seven sacks and Oakland has high hopes for safeties Tyvon Branch and Mike Mitchell, linebackers Trevor Scott and Travis Goethel, and defensive tackle Desmond Bryant.
The primary task for Bresnahan will be improving a run defense that has been a problem for years for the Raiders. Oakland allowed the fourth-most yards rushing last season at 133.6 per game and has the worst run defense in the NFL since Bresnahan left before the 2004 season.
Oakland has allowed 140.4 yards rushing per game over those seasons with a league-worst 139 touchdowns on the ground.
Oakland did finish second in the league in pass defense and was tied for second with 47 sacks.
During Bresnahan's tenure as defensive coordinator in Oakland, the Raiders ranked 17th in rushing defense (117.2 yards per game), tied for 14th in scoring defense (20.5 points per game), tied for 22nd in total defense (331.3 yards per game), tied for 17th in turnovers forced (117) and tied for 12th in sacks (152).
Bresnahan spent last season as defensive coordinator for Florida in the UFL. He has also been defensive coordinator for three years with Cincinnati and coached as an assistant with Indianapolis and Cleveland.