In between the second and third periods of Sunday night’s season-ending gut punch of a hockey game for the Washington Capitals, the video screen that hangs above the ice played the first portion of a team-produced documentary on Nicklas Backstrom. The images flipped from Backstrom raising the Stanley Cup above his head, then to the sea of red on Constitution Avenue — a perfect day for a parade. That was three years back.

Then came Backstrom, remembering.

“I want that feeling again,” he said, and quietly.

That feeling, it seems so long ago. And after the Boston Bruins dumped the Caps from these playoffs with their fourth straight victory in this first-round series — 3-1 in Game 5 at dejected Capital One Arena — it’s worth wondering whether that feeling will be back with this group. The Capitals’ last series win in the Stanley Cup playoffs came against the Vegas Golden Knights in 2018, a spring when they won four straight series for the only time in franchise history. Since then, they’re 0-3 — each one a bit more dejecting than the last.

Lose to the Carolina Hurricanes in double overtime of a Game 7 in 2019? Eh, whatever. Look at the Cup!

Lose to the New York Islanders — and that Cup-winning coach, Barry Trotz — in five quick games of the covid-delayed first round last summer? Well, Backstrom was hurt for most of that series, and who knows how the NHL’s Toronto bubble affected anyone? Move on.

But this loss would seem to bring larger questions about what’s possible for these Caps a year from now, three years from now, for the rest of the careers of Backstrom and forever running mate Alex Ovechkin. It had some of that old Caps energy — the pre-Cup variety, when dread settled over the building and the crowd started to fold in on itself.

Boston posted eight of the game’s first 10 shots. The Caps outshot the Bruins the rest of the way 39-11. At one point, the Caps had 14 second-period shots and zero goals, and the Bruins had three second-period shots — and two goals.

“It’s tough,” Coach Peter Laviolette said.

It’s lazy to say that kind of thing seems so Caps — so, so Caps — even when it feels exactly like that. In the third, trailing by two, Lars Eller looked as if he scored a momentum-changing goal on the power play. Instead, it was waved off because the officials deemed that Evgeny Kuznetsov had interfered with goalie Tuukka Rask — ensuring that Kuznetsov’s name would be called at least once in this series. (Whether he made a greater impact missing the first two games while on the covid-19 restricted list or when he played the last three — that’s debatable.)

But this wasn’t just about Sunday night. When seasons end with thuds like this — repeatedly — there’s a need to take in the long view and wonder why it keeps happening. It’s both obvious and important to say that the core is getting older, and …

Wait, before breaking that down, here’s a sentence that’s weird to read:

Alex Ovechkin could be a free agent this summer.

“We just lost in a playoff series,” Ovechkin said. Such talk, he said, is best for “later on.”

“This is his team,” Laviolette said. “That’s business that gets taken care of on a different day.”

No one expects a new contract to be a real issue. A deal is almost certain to get done, and Ovechkin should be pulling on the red sweater with the “C” on it come fall. When he does, he will be 36.

Given the conditioning and health habits of modern athletes, there’s nothing wrong with being a little, um, seasoned. Patrice Bergeron is 35, and he scored twice for the Bruins on Sunday night. Indeed, Boston has some gray in its core — David Krejci is 35, Brad Marchand 33, goalie Tuukka Rask 34. Plus, Ovechkin has shown that predicting his demise is foolish, and he probably has more good hockey — and many more goals — left in him.

But ask a different question: What player age 25 or younger contributed significantly for Washington in this series?

The only answers: goalie Ilya Samsonov and third-line winger Daniel Sprong, both 24, the only young-legged players given sweaters Sunday night. The Bruins can counter with budding star David Pastrnak, who dazzlingly slipped a puck between his 24-year-old legs — spinning around a helpless Nic Dowd — to open the scoring. But Pastrnak’s not alone.

Charlie McAvoy, who plays on the Bruins’ top defensive pairing, is 23. Forward Nick Ritchie is 25. Linemate Jake DeBrusk and defenseman Brandon Carlo are both 24. Even Jeremy Swayman, the backup goalie, is 22. Boston has a sprightly presence to offset the old heads.

Looked at another way: The Caps dressed 12 players 30 and older Sunday night. The Bruins dressed five.

But this can’t be simply as “younger team beats older team,” because it’s not that simple. Every time you think it’s the year when the Caps will look creaky and slow, they either win or very nearly win their division. And in this series, the only game in which the Caps looked significantly slower than the Bruins was Game 4. T.J. Oshie is 34, Backstrom is 33, Eller is 32, John Carlson is 31 — and they basically continue to get it done over the haul of a regular season.

Can they get it done again over a two-month spring?

“Those are questions that I think you gotta think about with regard to where your team’s at,” Laviolette said. “I can tell you this: the guys that were here, the core guys that you’re talking about, are a big reason why we had the success in the regular season that we did. They’re terrific players. … There’s frustration. I think everything gets looked at and evaluated, but those guys have been the cornerstone of this team for a long time, and they were of this team for the regular season.”

Still, we’re back at where we have been for the majority of the Ovechkin-Backstrom era: regular season juggernaut produces a winter of joy and hope. As much as the pre-Cup Caps were known for their playoff failures, they won at least one series four straight springs — from 2015 to 2018, when they broke through. Then the Hurricanes. Then the Islanders.

And now … this.

“It sucks,” Ovechkin said.

When the final horn blew and the Bruins began their hugs, Ovechkin tipped his helmet back on his head. Backstrom skated by himself into one corner of the rink, bent at the waist. Every season but 2018 has ended this way. The Cup still matters because it produced the memories and cemented legacies. But each year it’s further away, and none of us are getting any younger.