Thomas addresses the media.

Thomas addresses the media.

BOSTON — Boston Bruins goaltender Tim Thomas is approaching his 35th birthday later this month, but that didn’t stop general manager Peter Chiarelli from inking the two-time All-Star and would-be unrestricted free agent to a four-year contract extension worth a total of $20 million.

In explaining his decision at a press conference today at TD Banknorth Garden, Chiarelli pointed to the fact that even at his age Thomas hasn’t endured a lot of the NHL grind some similarly aged goaltenders have. But Thomas, as he often does, was quick to share the credit for his fantastic physical well being.

“I’d like to credit some of the improvement to the Boston Bruins staff — John Whitesides, strength and conditioning coach, (goaltending coach) Bob Essensa … and the trainers for keeping me healthy,” said Thomas, who leads the league in goals-against average (2.11) and save percentage (.932). “It’s been more than just me that’s allowed me to get better. That’s part of the reason I wanted to stay here.”

A big reason the Bruins wanted Thomas to stay is that Chiarelli believes that if Thomas can suddenly emerge as a Vezina Trophy favorite at 34, he could have bigger and better things in store in the years ahead.

“What I’ve seen from here on back, I’ve seen somebody who’s improved. And his level is at such a high level now, but he’s improved at this age each year. And he’s improved a lot,”  Chiarelli said. “So he’s gone from a high level to a higher level to a higher level, and he’s maintained that. It’s taken a while to get here, and he’s gotten here and he’s been tremendously successful, but the fact that he’s still improving and the fact that — I think — he’s got a lot of hockey left in him … just the fact that his perseverance and his dedication have allowed him to improve and to be such a competitive person has impressed me so much.”

Knowing that this contract would probably be his last, Thomas could’ve hit the open market this summer and signed with the highest bidder. The Detroit Red Wings, with questionable goaltender on their roster these days, might’ve been among  those making a big-time pitch. But Thomas says he never even considered the chance to return to his home state.

“I didn’t even really think about that because who knows, Chris Osgood could have a great playoff and then they’re not thinking about that anyway,” said the Bruins’  puck-stopper. “I’ve been in the Northeast since I was 18. I am a Michigander, I grew up watching the Red Wings, but I’m a Boston Bruin now, not a Red Wing. So it never really came into consideration.”

Some might take the Bruins’ long-term signing of Thomas as a sign they’re not as high on prospect Tuukka Rask as they once were. But with Manny Fernandez scheduled to become a UFA, there should still be a job opening in  Boston. And Chiarelli said that the plan is still the same for the younger goaltender’s progression.

“I would expect (Rask) would come next year and challenge for a spot. He’s part of our future. So I think he’s a positive kid. I’m sure he’s happy for Tim. …” Chiarelli said.

Figuring out where Rask fits in the future is the least of Chiarelli’s problems now. With Thomas on the books at $4 million more than he’s been making, the Bruins could be heading into a precarious situation salary-cap wise. Star forwards David Krejci and Phil Kessel, as well as emerging top defender Matt Hunwick, are scheduled to be restricted free agents this season. Getting everyone signed long-term, especially with the anticipation that the cap will come down for the 2010-11 season, will be a bit of a shell game for Chiarelli.

“This is our job. We have to figure out the puzzle, we have to make decisions,” said the GM. “I’d like to sign everyone, but we have to make decisions over the summer and we look at the performance of the players and then we do the math. We’ve been doing the math ever since I’ve come here and that’s a large part of the job.

“But what is important to the organization is that we have terrific goaltending for a long time. Sometimes you have to put aside the math, not completely, and make the decisions like we did with Timmy.”

The negotiations between Thomas’ camp and the Bruins, which were off and on over the last six months or so, obviously didn’t distract Thomas from his goal of becoming the best goaltender in the NHL. But even he admitted that with this deal signed and sealed, hockey will be an unchallenged top priority in his mind for what he hopes will be a lengthy playoff run.

“I’m very happy that this is done. I think I’ve done a really good job of just concentrating on hockey throughout the year even knowing that we have had talks off and on,” said Thomas. “But now this gives me a 100-percent chance to just focus on hockey and leave the rest of the stuff and not think about it. I think this gives me an opportunity to play to my full potential down the stretch here and that’s what I plan on doing.”