The truth is, he really hasn't.
He's always been dedicated and goal-oriented, and it's helped him gain all the success he's achieved. Thomas, who turns 38 on April 15, has always done it his way, no matter what he was told by coaches, general managers, players, teammates, fans or the media.
He has voiced his hockey and non-hockey beliefs publically, but because he's a two-time Vezina winner, the reigning Conn Smythe Trophy winner and a defending Stanley Cup champion, his words, whether written or spoken, have reached the masses.
Yes, he boycotted an invitation to the White House by President Barack Obama and gave his explanation via Facebook. Now when he's asked about it, especially with the Bruins facing the Washington Capitals in the first round of the Eastern Conference quarterfinals, Thomas has decided to remain mum and walk away.
Thomas believes what he believes. He's no different now than he was 10 years ago, when he was trying to prove to people that he could play and succeed in the NHL. His focus is to stop the puck. That's all the Bruins want him to do.
"I don't think he's changed at all," Bruins coach Claude Julien said. "You know, he's a guy who still continues to thrive on challenges and who always takes the negative and turns it into a positive and loves to prove people wrong and everything else. So he hasn't changed. I know there have been some incidents that might indicate that, but as a person he's still the same."
On the ice, there's no denying he's a great goaltender. His success and achievements should earn him serious consideration for the Hal of Fame once his career is over.
After a season of ups and down, Thomas still finished with a 35-19-1 record, along with a 2.36 goals-against average and a .920 save percentage. He's on the brink of another playoff run, and if he can repeat his performance from last spring the Bruins will be in good shape once again.
No matter the situation. No matter the final score of any game when Thomas is between the pipes, afterward he'll say his only focus was to stop the puck. That seems obvious, but the NHL game, especially in the playoffs, is so fast and intense that it can be easy for a goalie to lose focus and let the opponent get the best of him.
"I'm not always thinking about it in those exact terms of just stop the puck," he said. "That's my job, but with experience over the years, there are times when you try to do too much. There are times I've pressured it and try to create offense in my own way, trying to pass the puck up too much or trying to play the puck instead of taking a whistle.
"Basically, experience over the years has taught me, when it comes game time that I've got to focus on my job. Zdeno Chara has to focus on his job. Andrew Ference has to focus on his job, and when everybody does that as a group, that's when you have success. That same experience has taught me over the years that when other people are worried about whether other people doing their jobs, it's not the right way to go about it."
He spent a good portion in the early part of his pro career playing in the minors and in Europe. When he signed with the Bruins as a free agent, he was assigned to Providence of the AHL during the 2002-2003 season and had to battle for the starting job along with Bruins prospect Andrew Raycroft.
The Bruins eventually named Raycroft the team's No. 1 goalie during the 2003-2004 season and he won the Calder Trophy as the league's top rookie. Thomas spent that entire season in Providence and split time with another prospect, Hannu Toivonen.
Toivonen was 19. Thomas was 30.
Toivonen was slated to be the future between the pipes in Boston. Thomas was the insurance plan. The two forged a solid friendship despite the competition.
"Obviously, I was a young kid and being so young at that point and not knowing how everything is done in North America, he was a great help for me and guiding me through day-to-day things," Toivonen told ESPNBoston.com in a recent phone interview. "There's a big learning curve when you're a 19-year-old kid and you don't know how everything works. He helped me a lot and helped me to get started. He was a big help.
"It was a unique situation. We were definitely both competing for the job all the time, but that's the nature of pro sports. I enjoyed those years playing in Boston. I love Boston as a city and an organization and it'll always have a special place in my heart. I was able to play with a lot of great guys and Timmy was one of them."
During the 2005-2006 season, Raycroft, Thomas and Toivonen all played a significant amount of games. But the following season, it was Thomas who finally, at age 32, became a full-time goaltender in the NHL for the first time in his career.
He outlasted the prospects. He's proved the critics wrong. He's hasn't stopped.
"I'm really happy for him and what he's been able to accomplish," Toivonen said. "He's always been a true fighter on the ice. He's so competitive, and it's such a part of his nature, I'm sure that competitiveness has helped him achieve all these great things he has. I've always thought he was a great goalie. He's a special guy. On every puck, at every practice, he never lets up. He never gives up during the game. He's got that special fire in his belly that has helped him to win a championship, be the MVP and all the great things that he has achieved."
Thomas was one of the major reasons why the Bruins were able to hoist the Stanley Cup in 2011. He's play was incredible. He became only the second goaltender (Bernie Parent was the other) to win the Cup, Conn Smythe and Vezina trophies in the same season.
Thomas finished the 2011 Stanley Cup playoffs as the only goalie NHL history to win three Game 7s.
Can he repeat that kind of performance again? Toivonen for one doesn't see his friend and former teammate letting up anytime soon.
"I don't see it," Toivonen said. "He has a different style than most of the guys out there, but the fact that he competes so hard will allow him to play at that top level for years to come and I don't see a reason why he wouldn't be able to do that.
"Being a goaltender myself, and every other goaltender in the world can take a lot from Timmy and how he approaches the game. He's one of the best, if not the best, in that sense."