Traditionally, when a pro athlete sees Boston in their rearview mirror, there’s little chance they’ll return. Only a few can say they’ve enjoyed a second act on the New England stage -- Ellis Burks and Antoine Walker are among a handful of players who have launched their professional careers here, left, and then returned again.

Linebacker Tully Banta-Cain is the latest to try and find out if things can be sweeter a second time around. After four seasons with the Patriots, the California native left New England at the end of the 2006 season, drawn west by the lure of a three-year contract worth $12.2 million and the chance to play in front of family and friends in the Bay Area with the 49ers.

But what he found was a dysfunctional organization. When he was released in February after two years with San Francisco, it was a relief. And when the chance came to re-sign with the Patriots, he didn’t need much convincing.

“I don’t know how many guys get to go back to their alma mater, the NFL team where they started,” Banta-Cain said this week. “So I’m excited.

“Some of the stuff I know now I wish I would have known three years ago,” he added. “I think I’ve learned a lot in my career thus far, and I’m continuing to learn. But I’m definitely wiser than I used to be when I left here.”

Originally taken in the seventh round of the 2003 draft out of Cal, Banta-Cain is a 6-foot-2, 260-pound outside linebacker who was with the Patriots from 2003 until 2006, and won two Super Bowl rings. (He did lose one of them in a bathroom at a Providence mall, but got lucky when a fan returned it to him.) A situational linebacker who made his bones as a pass rusher, he had a knack for good timing -- his best season came in 2006, a contract year. That season, he played in all 16 regular season games, starting five of them and picking up a career-best 5½ sacks. For his efforts, he hit the open market and landed a rich new deal with the 49ers.

But the return didn’t go as he’d hoped -- the Niners were beset with several problems, and his game suffered. In his two years in San Francisco, Banta-Cain’s numbers were fair at best. He played in all 16 games in 2007, starting 10, and finished with 41 tackles and 3 1/2 sacks. He appeared in just 10 games last season (no starts) and managed just a half a sack.

He was cut on Feb. 10, and was re-signed by the Patriots eight days later, a one-year deal that could be worth roughly $700,000 if he meets all his incentives.

“I think I left on good terms,” Banta-Cain said. “I think with my situation in San Francisco not going the way that I expected it to, there was definitely light at the end of the tunnel for me to come back here, because I did leave on good terms. I was definitely looking forward to coming back, based on how unhappy I was in San Francisco.

“I think that when the opportunity presented itself, there was a mutual understanding between both parties -- myself and the Patriots -- who knew I left on good terms, and so I should be able to come back on good terms.”

Banta-Cain was present at this week’s Organized Team Activity, working with a handful of rookies, new veterans and other players who have a limited background in the New England system. While the 28-year-old acknowledges there are a lot of similarities to the team he left after the 2006 season, there’s still a re-adjustment period.

“It seems like they’re doing the same things they were when I left, so I don’t think it should be too hard to get back into the system,” he said. “But I’m definitely going through the learning curve getting back.

“There are a couple of new faces. They’re definitely trying some new things. But that’s how it’s always been. That would be the biggest thing -- just getting re-acclimated to what I used to be.”

The sooner Banta-Cain gets acclimated, the sooner he can start competing for the vacant outside linebacker position that became available when Mike Vrabel was dealt to Kansas City. If New England is unable to swing a deal for a veteran outside linebacker, there are a handful of players on the roster who could see time opposite Adalius Thomas. It’s a group that includes Banta-Cain, Pierre Woods, Shawn Crable and Vince Redd.

“I know that Vrabel played a big role in this defense, so with him being gone, there is an opening,” Banta-Cain said. “Whether that means I’m going to fill it or whoever, that’s to be determined. But I think that’s what motivating a lot of the guys here -- hey, there’s a great chance to step in and continue to help the team win.”