The move does not come without its risks as the Raiders gave up a first-round pick in 2011, which could be in the top 10 based on Oakland's recent history, to acquire a lineman who turns 30 next month and is in the final year of a contract paying him $3.7 million this season.
Raiders owner Al Davis wanted immediate help for a defense that has struggled to stop the run in recent seasons. Since going to the Super Bowl after the 2002 season, Oakland has had the worst run defense in the NFL, allowing 141.7 yards per game on the ground and 122 touchdowns rushing.
Seymour has been a stalwart in New England since being drafted sixth overall in 2001. He played on three Super Bowl winners with the Patriots, recording 39 career sacks and being selected to the Pro Bowl for five straight seasons beginning in 2002.
"It shows the commitment of this organization," defensive end Greg Ellis said. "You can't guarantee we're going to have a great, great season this year. But the commitment is definitely there, so players don't have to question that when you're making those kinds of moves to make something happen and hopefully win right now."
Seymour will primarily play right defensive end, shifting to tackle in some passing situations.
QB McCown passes physical with Jaguars
JACKSONVILLE - Quarterback Luke McCown passed his physical with the Jaguars , prompting the team to cut veteran backup Todd Bouman.
Jacksonville traded an undisclosed draft pick in 2010 to the Bucs on Saturday night in exchange for McCown, who was beat out for the starting job by Byron Leftwich.
The Jaguars will head into their opener at Indianapolis with little experience behind starter David Garrard and a backup still trying to learn the playbook.
Bills: Former offensive coordinator Turk Schonert told a Buffalo television station he was fired Friday because the offense "wasn't simple enough" for coach Dick Jauron. "He wants a 'Pop Warner' offense," Schonert said in a phone interview with WIVB. "He limited me in formations and limited me in plays. He's been on my back all offseason." Alex Van Pelt takes over.
Broncos: Veteran defensive end Vonnie Holliday, 33, who joined the team Saturday after playing last season for the Dolphins, had his first workout and told reporters surgery to an injured knee is what prevented him from signing a contract this spring.
Chiefs: Fourth-year safety Bernard Pollard and veteran linebacker Zach Thomas were among the 13 players released. Wide receiver Ashley Lelie, signed during camp as a speed threat, was waived.
Eagles: Veteran quarterback A.J. Feeley was released and rookie defensive tackle Antonio Dixon, a former Hurricane, was claimed off waivers from Washington.
Falcons: Quarterback D.J. Shockley, Atlanta's seventh-round pick in 2006, was among eight signed to the practice squad.
Jets: Quarterback Kevin O'Connell was acquired from the Lions for an undisclosed draft pick. O'Connell's arrival gives the Jets four quarterbacks - rookie starter Mark Sanchez, veteran Kellen Clemens and Erik Ainge.
Seahawks: Safety Lawyer Milloy signed a one-year deal. Milloy, 35, grew up in Tacoma, Wash., and played for the University of Washington before entering the NFL in 1996 with the Patriots. He spent the past three years in Atlanta.
Texans: Cornerback Dunta Robinson ended his holdout and signed the one-year deal the team had been offering all along. Robinson balked when he was tagged the franchise player, saying he wanted more than the $9.957 million that came with the tag.
Vikings: Quarterback John David Booty cleared waivers and joined the practice squad.