San Jose sent forwards Marco Sturm and Wayne Primeau and defenseman Brad Stuart to the Bruins, sacrificing three members of their young core for Thornton, a probable 2006 Canadian Olympian and three-time All-Star considered one of the NHL's top power forwards.
Thornton was stunned when general manager Mike O'Connell called his cell phone after Thornton had just finished dining with his parents in Boston. The 26-year-old signed a three-year, $20 million contract in August with Boston, where he was the club's captain for the last three seasons.
Thornton was less than complimentary of O'Connell and coach Mike Sullivan, whose jobs are both rumored to be in jeopardy.
"I was blindsided," Thornton said in a conference call. "On the one hand it's disappointing, and on the other it's good to start over again. When you don't win, there's going to be changes.
"Obviously [the Bruins] believe in their coach and their general manager, and I'm next in line, so I've got to move on. ... I came back here to win, and we haven't been winning. Whose fault is that? I'm not sure, but I'm out of here, so it must be mine."
Thornton was tied for 11th in the NHL in scoring entering Wednesday's games with nine goals and 24 assists, but Boston has lost nine of its last 10 games. The Sharks, who lost 4-1 to Dallas, are 0-7-3 in their last 10 games during one of the worst stretches in franchise history.
San Jose general manager Doug Wilson said he expects Thornton to be in the lineup Friday in Buffalo, where the Sharks will play the second game of a three-game road trip. Wilson agreed the trade was among the biggest in franchise history, alongside the trade of former captain Owen Nolan to the Toronto Maple Leafs in 2003.
"Players like Joe Thornton don't come available very often," Wilson said. "He's a big, physical guy with a lot of ability. He also knows a lot of our players very well. He should fit in well with our group.
"He's a special guy. The combination of he and [Patrick] Marleau down the middle should be very strong for us," Wilson said.
Thornton and Marleau, the Sharks' captain and leading scorer, were the No. 1 and No. 2 overall picks in the 1997 entry draft. Both joined the league that year as raw 18-year-olds but eventually emerged as top NHL centers and teammates on several Canadian national teams.
Thornton has scored more than 20 goals in each of his last five NHL seasons, including two 30-goal campaigns. In 2003-04, he led the Bruins with 23 goals and 50 assists.
Though Thornton is aware of the Sharks' recent struggles, he is encouraged by the Sharks' success in 2004, when they went to the Western Conference finals during the best season in franchise history.
"They had a great run there, and they've got great goaltending, obviously," Thornton said. "I know [Marleau], and he's a great centerman. Hopefully we can be a great 1-2 punch."
Thornton joins his cousin in San Jose, Sharks forward Scott Thornton. Their fathers are brothers -- and Joe Thornton's father already expressed his delight at the possibility of making road trips together.
"I obviously know him," Scott Thornton said in Dallas. "He's one of the top 10 players in the league. He's a big, powerful forward. I expect him to be a giant on special teams."
Still, Scott Thornton expressed regret in losing Sturm, Primeau and Stuart, who were last-minute scratches from the lineup in Dallas.
"We lost three great teammates," he said. "The bottom line is we're all to blame for this. ... We should all feel guilty about this."
The departing Sharks players, all first-round picks, are expected to play for Boston on Thursday night against the Ottawa Senators.
"We felt we needed to shake up the team and sometimes you have to make some difficult decisions to better the team," O'Connell said in a statement. "We feel we received three players who can help us immediately."
All three new Bruins are bona fide NHL talents -- but all three also had flaws that contributed to the Sharks' malaise this season.
Sturm is the Sharks' second-leading scorer with six goals and 10 assists this season, but the speedy German forward still hasn't developed into the top-flight goal-scorer most expected him to be. He missed the Sharks' playoff run in 2004 after breaking his leg late in the regular season.
Stuart, who has two goals and 10 assists, finished second in voting for the Calder Trophy as top rookie following the 1999-2000 season. But he has struggled for long stretches this season, prompting public criticism of his passing and physical play by coach Ron Wilson.
Primeau, a gritty fourth-liner, has five goals and three assists this season.