If the Washington Capitals have to face a Game 7, then let it be in Boston. There’s no better place for a visiting team that is haunted by its own playoff ghosts than a trip to New England, where curses revive themselves and any excuse for pessimism is greeted like a regional holiday.

If the Caps think that their fans sometimes cast a pall of anticipatory despair over them in crucial games, then they should remember that the Bruins operate under a similar and permanent handicap. Yes, the Bruins won the Stanley Cup last season after 20 years of, mostly, mediocrity. But, seriously, can one success erase New England’s 392-year-old disposition?

I just got back from a few days with in-laws in Massachusetts. I’d forgotten. Or maybe I thought that those seven titles between 2001 and ’11 by the Patriots, Red Sox, Celtics and Bruins had somehow altered a sports-addicted culture where defeat and guilt are intertwined in a unique way.

For generations, New Englanders have used the losses of their teams as a coping mechanism. If the Patriots lose, you vent your anger. If the Bruins blow it, you bond over the shared loss. If the Red Sox revert to their time-dishonored character, you use it as material for comedy.

Boston fans have developed a cheerful kind of dyspepsia that I’ve never encountered anywhere else. They turn heartbreak into mere heartburn then, like last Friday’s 100th anniversary of Fenway Park, into deep, heart-felt bonds that ignore generations of actual results. I observed it for four years in college, then 28 years since marrying into a family of Boston sports addicts.

For New England fans, no matter what misery they mime, everything is turned to their advantage in a way that does more good than harm, adding to their sense of community and interconnectedness. They’re not nuts — just the opposite. However, their attitude is often an anchor to their teams.

When I returned home, I wore a ballcap given to me by my father-in-law, an ex-pro athlete. It had a Red Sox “B” on the front but was done in Bruins colors, linking and mingling the identity of the two teams.

“Probably won’t do either of ’em any good,” said one of my father-in law’s elderly buddies. Later, at a bar in Andover, I sat next to a young Boxford cop and his friend. The Bruins had just lost to the Caps in Game 5 and, minutes before, the Red Sox had turned a 9-0 lead into a 15-9 loss to the Yankees just one day after losing at their own 100th anniversary party.

The two guys looked at my hat. “What is that, a joke?” said the cop. “The Red Sox [stink] and the Bruins are dead,” said his friend. I didn’t feel chastised. I felt included, approved and ready to boo Bobby Valentine.

Moods change. The Bruins won Game 6 in overtime. And, last season, the Bruins became the only team to win three Game 7s in a Stanley Cup trek. But in New England, optimism is measured in teaspoons while gloom comes in buckets and doom arrives in its own 18-wheel rig.

If the Bruins start well Wednesday, get ahead and have the Caps on the ropes, then the TD Garden crowd will boost them even higher. However, if Game 7 is as ridiculously close as every other battle in this series, then the nervous energy and mounting frustration in the Garden should work to the Caps’ advantage.

New England adores history, but views it with a Puritan tilt, a distrust of any display of unearned joy — like optimism in advance of an actual final score. As soon as Caps goalie Braden Holtby got hot, the Boston Globe obligingly noted, “Remember unheralded rookie goaltender Steve Penney and the Canadiens sweeping the heavily favored Bruins in 1984?”

“Picking” the Caps in a Game 7 is just inverted showboating. Every time I review their accumulated failures since 1983, I’m dazzled, even though I covered almost all of the worst of them. You start to repress memories, such as their 2-7 mark in Game 7s or the seven times they have blown a two-game lead in the playoffs in the last 26 years.

However, one atrocious April distinction, out of all the Caps’ indignities, may be pertinent now: The Caps have lost a playoff series in which they had home-ice advantage 13 times, including each of the last four years. They had home defeats in Game 7s in ’08, ’09 and ’10. So why not go to Boston?

From afar, you’d assume that the Bruins are delighted to come home and that it is almost certain to help them. Think again. All sports karma in Boston is intertwined and the worst possibility gets the benefit of the doubt.

The Bruins will have a home-ice advantage right up until the moment when the finally healthy Capitals give the packed house a reason to doubt, to bond in anticipation of defeat, to prepare their Bruins jokes for their coworkers in the morning. In this series, where both home arenas can turn into haunted houses, the visiting team has a four-games-to-two edge.

In what has been a stellar, taut series, the slightest factors have proved pivotal. With Presidents’ Trophy winner Vancouver already eliminated and the top-seeded Rangers facing a Game 7 of their own, the Caps-Bruins winner could go a long way this spring.

The Caps have three factors in their favor. They are underdogs (on merit), and that reduces pressure. They’re not at Verizon Center, where their dismal history is always pushed flush in their faces. And they are performing at TD Garden, a fickle venue full of New England mood swings that is not nearly as friendly to the Bruins’ psyches as the Caps’ followers may assume.

Boston is the town where sports karma, whether running hot or cold, can be infectious. Right now, it’s gettin’ chilly. And I’ve got the hat to prove it.

For Thomas Boswell’s previous columns, go to washingtonpost.com/boswell