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 following 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. The Raiders have allowed a 100-yard rusher in more than half of their games the past three years.
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.
"From nearly the day he arrived in 2001, Richard Seymour established himself as one of our premier players for nearly a decade," Patriots coach Bill Belichick said Sunday. "His presence has been felt as a force on the field, a respected man off it and a multiyear champion."
The move is the latest as the Patriots continue to get younger on defense.
Linebacker Mike Vrabel was traded to Kansas City in the offseason, safety Rodney Harrison retired, and Tedy Bruschi officially called it a career after 13 seasons. Seymour was the last member of the 2001 Super Bowl championship defense still with New England.
Earlier this summer, Oakland sent two-time Pro Bowl defensive end Derrick Burgess to New England for a pair of draft picks. The Pats also acquired receiver Randy Moss from Oakland in 2007 for a fourth-round pick.