The 2005-2006 season proved to be an unlikely breakout year for Thomas in the NHL. After a disappointing performance at the Bruins training camp, Thomas was assigned to the Providence Bruins in the AHL. During this time, Boston's two main goalies, Andrew Raycroft and Hannu Toivonen, were sidelined with injuries. Thus, Thomas earned his first call-up to the NHL in 3 years. During this time, he has taken over as the Bruins starting goalie, with record of 12-13-7 with 2.77 goals against average, a 0.917 save percentage, and one shutout at the end of the 2005-06 season. Thomas also won the Boston Bruins 7th Player Award for the 2005-2006. The 7th Player Award is given annually to the Boston Bruins player that the fans vote on as having gone above and beyond expectations for the season. Thomas signed a 3-year deal with the Bruins in March of the 2005-2006 season.

 

The Bruins traded Andrew Raycroft to the Toronto Maple Leafs for prospect Tuukka Rask during the 2006 NHL Entry Draft. Toivonen, who was designated as the starting goaltender at the beginning of the 2006-07 season, suffered in his appearances at the NHL level, where he finished the year 3-9-1 with a 4.23 GAA and .875 save percentage. Thomas was again promoted as the Bruins' starting goaltender, posting a 30-29-4 record with a 90.4% save percentage, having Toivonen, Brian Finley, Philippe Sauve, and Joey MacDonald alternating backup duties. He again won the 7th Player Award in 2006-2007, the first goalie in team history to win it twice.

 

On July 1, 2007, the Bruins acquired goaltender Manny Fernandez from the Minnesota Wild, while soon after trading Toivonen to the St. Louis Blues on July 23, 2007. Many hockey analysts presumed that Thomas would support Fernandez as a backup goaltender for the 2007-2008, or at least enter a Number 1-1A goaltending system, with Fernandez being higher on the depth chart. Not uncommon to what Thomas saw the two seasons prior, Fernandez got off to a sluggish start, posting a 1-1 record with 5.01 GAA and a 79.6% save percentage in his first two appearances. Therefore, Thomas again was thrust into the starting role, as he posted a 3-1 record with a 1.26 GAA and a 96.2% save percentage in his first four appearances. He currently leads the NHL in save percentage with a 93.6% save percentage