“I think they’re all different situations,’’ Thornton said of Wade Belak, Rick Rypien, and Derek Boogaard. “Obviously a tragedy, each one of them. But I think they’re completely different incidents. The only common denominator is that they all played hockey and had sort of the same role.

“I think people are always looking and trying to find something. I knew a couple of them. I was absolutely heartbroken and at a loss for words when they happened. But I don’t think taking this as an opportunity to exploit part of the game is the right way to go.’’

In some circles, the bare-knuckle duties of players such as Thornton are coming into question. The long-term health of fighters was already under scrutiny because of the chronic traumatic encephalopathy diagnosed in the brains of Bob Probert and Reggie Fleming.

Now, in the wake of Belak, Rypien, and Boogaard, the prickly issue of fighting has exploded once more. And if there is anything constructive emerging from the deaths of the three tough guys, it’s that people inside and outside the game are thinking, talking, and fretting over its purpose.

There are the usual parties at both ends of the argument. Ban fighting immediately, says one camp. Keep it in the game, says the other.

Short-term, there will not be a consensus. But the underlying issue that has been pushed to center ice is how difficult the enforcer role can be. And not just because a tough guy is at risk of having his nose bashed in every time he steps off the bench.

Perhaps more difficult is the mental trauma that only a fighter understands. There’s the day-before buildup, knowing that a pounding might take place the next night. There’s the day-of roiling that strikes a player’s stomach and turns the pregame nap into a waste of time. There’s the bloody skate to the penalty box - or worse, to the dressing room for repairs - after your hated opponents and 20,000 of their fans watched you get your eyes blackened by a player who proved to be bigger and badder.

“It’s been a tough job forever,’’ Thornton said. “It’s not easy going into a game knowing you potentially might have to fight somebody 6 foot 8 and 250 pounds. But that’s [expletive] common sense. I don’t think anybody would think that was easy. That’s nothing new because of what happened. It’s a tough job.’’

The fear used to catch Thornton with more force earlier in his career. As he was shaping his identity, he was more of a scrapper than a hockey player. In 1998-99, Thornton piled up 354 penalty minutes in the AHL.

Thornton acknowledged struggling through sleepless nights because of the strain of the job. Even last year, he acknowledged having some concern before games against the Rangers, knowing Boogaard and his thunderous fists were waiting to fly.

“Obviously I’m a little biased, but I think it’s the toughest job in the league,’’ Thornton said. “That’s why I try and play fairly honest. I have a lot of respect for everyone else in the league that does it. Whether I like them or I don’t, I have a lot of respect for every guy that has to do this role.’’

Thornton’s transformation began in 2001-02. That year, he played for Trent Yawney in Norfolk, Chicago’s AHL affiliate. Yawney’s message: The fighting will take care of itself. Focus on playing hockey.

Yawney’s message stuck. As Thornton diversified his portfolio, he developed into a tough guy who could forecheck, create scoring chances, and play responsible defense (10-10-20, 14 fights, 10:04 average ice time per game in 2010-11).

Thornton was a healthy scratch for Games 1 and 2 of the Stanley Cup Final. During those two losses, the Bruins’ fourth line was a unit lacking in purpose and identity.

It was no coincidence that after Thornton made his series debut in Game 3, the fourth line led the thump parade. Thornton never dropped his gloves in the playoffs, but he was a powerful presence.

It was that expansion of his skills, Thornton guesses, that helped him reduce some of the stress of fighting.

“That’s why I’ve gone out of my way to not make that my identity,’’ he said. “I’m very fortunate that I get to play meaningful minutes.

“I worked my whole life to not be that guy. When you do it, you’re always going to have that label. That is my role. I have no problem doing it. Whatever needs to be done, I’ll be the first guy to try and get it done.

“But I’ve really worked my whole life to be more than a one-dimensional player. Over the last few years, I think people have noticed I’m not a 3-4 minute guy.’’

Naturally, Thornton believes fighting belongs in hockey. He has repeatedly stated three reasons for it: to stick up for yourself, defend your teammates, and provide an emotional trigger when needed.

In these dark days, not everybody agrees.

Krejci, 25, is entering the final season of a three-year, $11.25 million contract. Now that Marc Savard’s career is most likely over, Krejci should be the club’s No. 1 center for at least the next five years.

During the 2010-11 regular season, Krejci wasn’t as consistent as a top-line pivot should be. In 75 games, he had 13 goals and 49 assists for 62 points. But in the playoffs, Krejci brought the good stuff, submitting a 12-11-23 line in 25 games to lead the Bruins in scoring.

Is Krejci one of the game’s elite centers, among the likes of Pavel Datsyuk, Steven Stamkos, Henrik Sedin, and Jonathan Toews? No, but he could be in a second or third tier, with Nicklas Backstrom, Mikko Koivu, and Mike Ribeiro.

In the postseason, Krejci showed he can jack up his game, and he should continue to improve and perhaps become a point-per-game player.

Last year, Krejci saw his penalty-killing duties wane. While he prefers to play in all situations, breathers during opposing power plays could make him more dangerous in offensive scenarios.

“He had a terrific playoff,’’ said Bruins general manager Peter Chiarelli. “He’s progressing like we projected he’d be progressing. He’s still a terrific young player. We’re very deep at center. We built our team, whether Savvy’s here or not, to be deep at center.’’

This will be the first season of Bergeron’s three-year, $15 million contract. Krejci should receive a similar deal, with, most likely, a no-movement or no-trade clause.

Breaking news The chorus among NHLers, especially of the dangling variety, has been for lighter sticks. The manufacturers listened, and today’s one-piece graphite models are the lightest they’ve been, resulting in heavy, whiplike snap shots. But virtually every player has learned the hard way that those sticks snap at the worst times. It’s commonplace to see a player throw away shards of his stick just as the opponent starts an odd-man rush. It’s also a regular occurrence to see the faces of general managers go white when their equipment managers submit the stick bills. But several stick manufacturers are beginning to hear from sheepish players who admit their pieces are too light. If that’s the case and builders return to stiffer sticks, the shoot-and-shatter days may have seen their peak.

Shining moments We puckheads acknowledge that hockey, at least south of the Canadian border, remains a niche sport. But one thing the NHL does miles better than other sports is celebrate its most prized possession. Aside from its pursuit, there is nothing better than the Stanley Cup’s 100-day tour in the stewardship of the victors. It’s not only the joy the Cup brings to the players, but to the friends and family with whom they share it. The entire spectacle is dead-on perfect, like a slap shot struck just right.

Old friend still missed Hard to believe that good friend Jack Falla has been gone for three years now. It was a rotten day around here three Septembers ago when word got out of Falla’s death. The proprietor of the Bacon Street Omni is still very much missed by his family and friends, of which there are many. Funny that, considering one of Jack’s classic lines: “I don’t want to meet anybody I don’t already know.’’

Loose pucks Bruins equipment manager and resident gearhead Keith Robinson was planning to host the Cup July 17. Robinson, a New Hampshire native, would have brought the Cup to New Hampshire Motor Speedway in Loudon, which was hosting NASCAR’s Lenox Industrial Tools 301 that day. But Robinson’s day was rescheduled for earlier in July. It’s a good bet the Cup would have been more popular than Dale Earnhardt Jr. during driver introductions . . . Old friend Steve Begin earned a tryout bid with Vancouver. Begin could be centering fellow ex-Bruin Byron Bitz on the Canucks’ crash line if both make the roster . . . Shane Hnidy will not have his name engraved on the Cup, said Chiarelli. The GM said Steven Kampfer also might not find a home on it . . . No surprise that ex-Bruin Mark Stuart was one of the four Jets modeling the Winnipeg franchise’s new jersey. Stuart will be one of Andrew Ladd’s alternates sooner rather than later . . . It was a tough stretch for some local rink owners when Tropical Storm Irene knocked out power around New England. Without juice, sheets melted and owners lost valuable ice time . . . On Monday, during Andrew Ference’s Cup celebration, a flash mob converged on the North End. Call me old and irrelevant, as many have, but the concept of flash mobs is beyond my comprehension. Anybody young and cool enough can send along an explanation, preferably via carrier pigeon . . . With summer on its last legs, it’s a good time to remind readers that the best way to fire up a backyard grill is with several crumpled newspaper pages. Try that trick with your iPad . . . After a well-deserved summer pause, colleague Kevin Dupont will be back at the wheel of the Sunday notes next week. Very pleased to hand back the keys to the bus’s owner. Could never turn off the left-side blinker, get the thing above 55, or eliminate that bad-coffee smell.

Fluto Shinzawa can be reached at fshinzawa@globe.com; material from interviews, wire services, other beat writers, and league and team sources was used in this report.