The three-year, $13.5 million contract could increase in total value to $18 million if Banta-Cain reaches certain incentives, according to a source. The deal includes a $6 million signing bonus and a $1 million base salary in 2010, meaning that Banta-Cain will earn $7 million this season.
"I was just happy," Banta-Cain told the media after the deal was announced. "It was a long day, and it's been a long process to get it done. I'm just relieved really. Now I can just focus on the football part of it. The business part of it is pretty much done."
The new contract represents a healthy raise for Banta-Cain, who signed a one-year deal for the veteran minimum last season and led the Patriots with 10 sacks in 2009.
Banta-Cain played in all 16 games last season. Initially projected as a sub rusher, he emerged as a contributor on early downs as well, playing in 66 percent of the defensive snaps.
"It's just real humbling. It just shows that you never know, and what a difference a year can make," he said. "Where I was at last year and where I was at this year, I'm in a different place now. I think the perseverance that you have to go through ... there is always going to be some kind of adversity and it's something that you have to go through in this business. I've treaded some rocky waters and I'm glad now that I know where I'm going to be and I've gotten through a lot of it."
Given that the pass rush was inconsistent last season, and Banta-Cain was one of the bright spots, losing him would have put the team in an even tougher position than it already was entering the offseason.
There weren't many attractive options on the open market to replace Banta-Cain had he gotten away. That factor, coupled with a solid bounce-back season, strengthened Banta-Cain's position in negotiations.
"I was honored to get the opportunity to come back. Not many people get to come back to where they originally started. It was definitely a big opportunity for me and I always looked at it that way. I really wanted to make the most of the season this year. Despite the way things turned out for the team overall, I was able to have a significant role in the season and I'm definitely satisfied with where I ended up because of where I started. It was a great experience to come back and now I'm really looking forward to my future here."
Banta-Cain started 10 of 16 games last season and in the perfect Patriots world, he'd probably be used as a spot starter and sub rusher. But with questions at outside linebacker, he would probably be a starter if the season began today.
Banta-Cain said he hadn't talked with other teams because he wanted to stay in New England. "The consideration was there but I really wanted to stay here. I love it here. That was the whole reason why we didn't want it to get that point where I would have to go to the free-agent market. My goal was to get something done here. I'm really glad that it happened."
ESPN.com senior NFL writer John Clayton and ESPNBoston.com Patriots reporter Mike Reiss contributed to this report.