“See you next year,’’ said one unrestricted free agent as he shook hands around the room. “If they don’t kick me out of here.’’

Seems so quick that a season just one win from being extended had been cut short by a Philadelphia club that didn’t understand the meaning of quit.

“Disappointed,’’ said Johnny Boychuk, “is an understatement.’’

The Bruins, who delivered their latest below-the-belt boot to their long-suffering fans, will not soon forget the garish facts of the Eastern Conference semifinals. Leading, 3-0, in the series. Up, 3-0, in the first period of Game 7. Losing the game, after all things, getting caught with too many men on the ice in the third period.

And now, the 2009-10 Bruins will walk forever in infamy, having gagged away a game and a series in a manner that cannot be denied.

They choked.

“The bottom line is that we had a 3-0 lead in the series. We had a 3-0 lead tonight. And we blew both,’’ said coach Claude Julien. “There are no excuses. We have to take the responsibility that goes with it. Everyone.’’

The 4-3 loss before 17,565 at TD Garden hinged on a botched change. Marc Savard was headed off. Vladimir Sobotka rolled over the boards to replace him. But for some reason, Savard stayed on, the Flyers rapped their sticks against the boards to notify the officials, and Thornton found himself in the penalty box at 11:10 of the third period to serve the most ignoble of penalties. Gagne took the gift and shoved it down the Bruins’ throats by beating Rask (23 saves) at 12:52.

The truth, however, is the Bruins lost the series well before six skaters were caught on the ice. In a thunderous first 15 minutes, the Bruins pasted every Flyer in sight and grabbed a 3-0 lead that should have been their chokehold on the game and the series. With Scott Hartnell in the box for high-sticking, Michael Ryder scored at 5:27 to give the Bruins a 1-0 lead. Less than four minutes later, after carrying the puck deep into the right corner, Dennis Wideman spotted Milan Lucic at the far post for a power-play tap in at 9:02.

Lucic capped the first-period explosion with a snap shot between Michael Leighton’s pads at 14:10. It was the sprint out of the blocks that coaches dream of.

“We were extremely pleased with the way we started the game,’’ Julien said. “We started the way we wanted to start it. We had lots of energy, we got a 3-0 lead. That’s something we wanted to do tonight — come out that way.’’

But the Bruins removed their blades from their opponents’ throats and played as if they were thinking about La Belle Province in springtime.

The gag job started late in the first when Savard and Miroslav Satan — indifferent, at best, in the defensive zone throughout the series — couldn’t clear the puck along the wall. Claude Giroux gained control, and with Savard and Satan out of position on the backcheck, Giroux found James van Riemsdyk in a seam in front. The big wing snapped a shot that busted Mark Stuart’s stick, changed speed, and dribbled past Rask at 17:12 of the first.

“Just because we were up, 3-0, doesn’t mean the game was over at all,’’ said Lucic, whose second strike prompted Philadelphia coach Peter Laviolette to call time out. “Not much more to say. They stuck with it. They came at us and came at us. They were relentless. They did what they needed to do.’’

As dominant as they were in the first, the Bruins were just as inept and legless in the second. At 2:49, after Rask booted out a Ville Leino shot, Hartnell tucked home the rebound. At 8:39, after the Bruins killed a Savard hooking penalty, Danny Briere whipped around the Bruins net and banked a shot off Matt Hunwick that caromed past Rask for the tying goal.

Surprise, surprise — the club that showed faster legs and more desperation had tied the score to set up the mother of all power-play goals in the third.

“The team that won tonight deserved it,’’ said Julien. “Let’s not forget that. They worked hard. They got themselves back in. They got some healthy bodies back and became stronger and better as the series went on. They found a way to win it.’’

The unraveling took place throughout the series. Marco Sturm blew out his knee in Game 1. Flyers captain Mike Richards ended David Krejci’s season in Game 3. After Mark Recchi tied Game 4 during six-on-five play in the third period, Chara threw an errant pass that resulted in Gagne’s OT winner. There were seven games of net-crashing abuse and wave-after-wave ferocity that ultimately wore out Rask, leaving little left in the rookie’s tank.

“I don’t have answers,’’ said Savard. “We came out four lines and were just pumped. Fans were incredible. Looch was incredible there. We were just working. We had chances all first period. And then, just kind of, I don’t know. I don’t know.’’