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Tommy Kelly feels like a rookie again.

After spending his first nine seasons with the Oakland Raiders — starting every game the past five years and six of the last seven — and even earning a captain's badge in the process, Kelly now is embarking on a new chapter in his career with the Patriots.

Yet despite signing a two-year deal in April to help bolster New England's front four, the 6-foot-6, 325-pound defensive tackle isn't exactly ready to buy a house in the area anytime soon.

"That's how I feel right now coming in, undrafted free agent. Ain't nothing guaranteed to you," Kelly said Wednesday during the second week of organized team activities. "You're the bottom of the totem pole. You can easily be replaced.

"NFL stands for 'Not For Long.' If you ain't handling your business, they'll get rid of you real quick."

In nearly a decade playing in Oakland, Kelly never took part in a postseason game. Even worse, he never experienced a winning season. The 32-year-old undrafted free agent now is suiting up for a team that lost in the Super Bowl two years ago and was within one victory of returning to the big game last year. So, it's hard not to ponder the possibilities of greener pastures.

All of that is secondary to him, though. For now, Kelly just wants to stick around for the regular season.

"Bill, he don't guarantee nobody nothing," he said of New England coach Bill Belichick. "So, I've got to get on the team before I start thinking about that.

"You see how many people they get rid of around here? Make the team first and then think about all that."

The Patriots certainly liked the thought of adding a dependable, veteran pass rusher to line up alongside perennial Pro Bowl nose tackle Vince Wilfork when they signed Kelly, released by the Raiders in a cost-cutting measure.

And he couldn't be more pleased to have landed in New England.

"Sometimes, change is good," Kelly said. "I was ready for the change. I'm very happy."

Lining up next to Wilfork played a pivotal part in signing with the Patriots.

"I love Vince," Kelly said. "He's easy to play with, makes my job much easier. . It's easy to play with somebody who's got experience and they can really, really play. It's love right now."

And of course, Belichick factored into his decision, too.

"When you're dealing with a coach with the resume of him, and if somebody like that believes in you, it makes you feel good about yourself," he said. "But at the same time, this is a program where you've got to prove yourself. If you don't prove yourself, he'll get rid of you."

That may be hard to believe in Kelly's case.

His sacks dipped from seven in 2010 and 7½ in 2011 to just one last season, but there's one thing Kelly can't be criticized for. No matter Oakland's record — whether a 2-14 campaign in 2006 or back-to-back 5-11 seasons in 2008 and 2009 — Kelly kept playing, week after week ... healthy or not.

"It's big when you play D-tackle, you've got to be reliable. It's a physically draining and mentally draining position," he explained. "I really pride myself on just being dependable and I'm going to give my teammates all I've got. So, if you've got somebody that you can rely on, it makes your job much easier."

It shouldn't take long for his new teammates to embrace his passion — if he makes the team, of course.

"It don't matter what the record is. Like I always say, your tape is your resume, and I wouldn't be in this league 10 years, an undrafted free agent, if I didn't play hard," Kelly said. "My teammates, they'll see that. Anybody I've played with in Oakland, knows that. I'm going to play hard and give it all I've got.

"I think I'll be all right."

As for a leadership role with New England, Kelly knows those captain patches have long been stitched onto other jerseys.

"Pretty much here, the leaders are already set with big Vince and Tom (Brady)," he said with a laugh. "So, I just fall in, do my job and don't be a distraction."