The Bucs were attempting to re-sign Darby, who was an unresticted free agent, but couldn't compete with Seattle, which had more salary cap room available. Denver, New Orleans and Atlanta were also interested in acquiring Darby.

The 6-foot, 293-pound Darby had his best season as a pro, notching a career-high 56 tackles and recovering a fumble as the team's starting nose tackle for all 16 games.

Darby posted 109 tackles, two forced fumbles, four fumble recoveries and 5.5 sacks in his four seasons in Tampa Bay.

His departure leaves Damien Gregory as the likely starter at nose tackle if the season were to start today. The Bucs are expected to continue to address the nose tackle position in the NFL Draft and in free agency. Former Oakland run-stuffing nose tackle John Parrella is a free agent and could be an option.

Darby is the third starter on Tampa Bay's defense to sign with another team, joining safety Dwight Smith (New Orleans) and linebacker Ian Gold (Denver).

In other news, it appears as if the Seahawks are upping their offer to former Bucs wide receiver Joe Jurevicius in order to lure him to the northwest. Jurevicius has been meeting with the Seahawks for the past two days and appears to be on the verge of signing with Seattle, but does have an offer on the table to return to the Buccaneers.