Banta-Cain released by Patriots

Bill Belichick's decision to go back to a 3-4 defense is apparently causing some roster adjustments at linebacker.

According to a source, the New England Patriots released veteran linebacker Tully Banta-Cain -- a 2003 seventh-round pick whom the Patriots brought in during the offseason -- in a surprise move Monday. On Sunday, Belichick de-activated linebacker Adalius Thomas, who was healthy but apparently not needed in the 3-4 scheme Belichick used in beating the Titans 59-0.

Last week, the Patriots re-signed 40-year-old Junior Seau to be a key backup for the 3-4 defense.

Banta-Cain, 29, spent his first four NFL seasons with the Patriots, mostly as a backup. He had five starts in 2006, which helped him secure a free-agent contract with the 49ers. Banta-Cain had 10 starts for the 49ers in 2007 but was a backup last season. After he was released by the 49ers this offseason, the Patriots gave him a chance to come back to New Engtland.

He started two games for the Patriots this season and had 13 total tackles.

It is also possible that the team could re-sign him in the near future.

John Clayton is a senior writer for ESPN.com.