The Bruins' promising postseason went down in blue and orange flames at Nassau Coliseum on Wednesday night, when they did not have enough offense, defense or goaltending to answer what the New York Islanders threw at them.

The Islanders broke open a 1-1 game with three unanswered goals in the second period to eliminate the Bruins in six games with a 6-2 victory and hurl the B's into an offseason of great unknown.

This team's championship window has been closing for several years and now, with key veteran players heading into unrestricted free agency this summer, there is barely any air getting in through that crack.

"Opportunities when you can win and have a really good team, they don't come around that often," said Brad Marchand, whose two power-play goals were the only offense the B's could muster. "That"s what makes it so tough. We felt like we had a really good group this year."

David Krejci, Taylor Hall (not able to do much later in this series), Mike Reilly, Sean Kuraly and the injured Kevan Miller will all be UFAs. But leading the list of unrestricted free agents is Tuukka Rask, the B's all-time winningest goalie who did not do much to reward coach Bruce Cassidy's decision to go with him over rookie Jeremy Swayman. It will surely be one that will be kicked around for a while. Both Cassidy and Rask acknowledged whatever the injury is could lead to offseason surgery.

Rask allowed four goals on 22 shots in the first two periods and, while the defense was quite shoddy in front of him, two goals came off big rebounds and a third by his own bad pass.

It was a tough ending to a difficult, injury-marred season for Rask. Time will tell us if it was the end of anything else.

"Listen, it wasn't good enough to win, but neither were we. So this isn't on Tuukka," said Cassidy of Rask's performance. "When you lose the Millers and the (Brandon) Carlos, guys who play big minutes for you and other D come in, other people in the lineup have to do their job and pick them up, whether it's the forwards scoring more goals or the goalie keeping the puck out of the net better or we defend better. And it's a mix of all those things. Of course he could have been better. There were some rebounds that we could have cleared or controlled better. It started there. But we mismanaged some pucks and put him in bad spots as well. This is a team loss."

As expected, the Islanders came out hard but the B's withstood the initial surge. Rask looked fine in the early going, making a good post-to-post stop on a Matt Martin backhander.

But the Islanders did get the first goal of the game. The B's third line iced the puck twice and, on the ensuing faceoff, Jean-Gabriel Pageau beat Charlie Coyle, getting the puck back to Noah Dobson at the right point. Rask made the initial stop on Dobson's shot, but Travis Zajac beat Charlie McAvoy to the rebound in the slot and beat Rask with a wrister at 8:52.

Cassidy was $25,000 lighter in the pocket for criticizing the officials after Game 5 for some missed calls, and his diatribe didn't immediately pay off as an obvious Adam Pelech leg trip on McAvoy was ignored early in the game.

But eventually, the refs had to blow the whistle. First Anthony Beauvillier was called for tripping McAvoy behind the Bruins' net on a pretty easy call. Then, with 14 seconds left on that penalty, Casey Cizikas tripped Hall at the offensive blue line.

The B's did not score on the short five-on-three, and it appeared as though the Islanders were going to grab a huge momentum shift by killing off the second penalty before the B's cashed in at 17:36. Matt Grzelcyk made a nice backhand keep-in at the right point and moved it to David Krejci. Krejci set up David Pastrnak for what looked like his countryman's patented one-timer. But Pastrnak fired a hot cross-ice pass to Brad Marchand on the right side and Marchand buried it past Semyon Varlamov.

But as was the case in three of the four Bruin losses, the Islanders dominated the second period.

The Isles had made it clear they were going after McAvoy in the first, and then Palmieri threw a clear cheap shot after the whistle early in the second period. Palmieri had a partial break and, after Rask gobbled up the rebound, Palmieri threw a shoulder into McAvoy's head. There was no call. The defenseman would need attention and then go to the room before returning to the game after missing about six minutes.

But before McAvoy came back, the Isles regained their lead when the miscues began in earnest. Grzelcyk tried to make a play on a rolling puck at his blue line and Brock Nelson swiped it off his blade. The Islanders center moved in all alone and beat Rask with a forehand shot at 5:20.

Then the Isles took a 3-1 lead at 12:29 on a bad play by Rask. He came out behind his net to play the puck and gave a hard, short pass that Mike Reilly could not handle. After it exploded off Reilly's blade, Josh Bailey grabbed the loose puck, dished it to Nelson and he tucked it home.

"I decided to go forehand and it ended up bouncing right before him. It was what we call a grenade," conceded Rask.

The wobbly wheels then came off at 16:07. Pelech fired a shot that Rask could not control but the rebound went right to Grzelcyk. Before he could pick his head up, Palmieri swooped in, knocked it off his blade and into the net.

For the second game in a row, the B's found themselves down by three goals, and they would not have their faithful fans rooting them on for a third-period comeback.

Just as they had in Game 5, the B's took advantage of an early third-period power play, with Marchand notching his second of the game at 5:30.

But the Islanders clamped down after that and with 58.9 seconds left, Cal Clutterbuck, who changed the series with his hit that knocked Carlo out, sealed it with an empty-netter. Ryan Pulock added another freebie to get the Long Island party started.

Now the B's have to look into an uncertain future well before they'd hoped they would.

"We're all getting older and we're not going to last forever," said Rask. "(The window) is definitely closing at some point. But you build a new team every year and come together and I thought we did that pretty good this year."

But whether all the old building blocks remain for next year is anyone's guess.