Harrison Barnes scored 31 points in the Mavericks’ 113-99 win Tuesday. (Toni L. Sandys/The Washington Post)

After the Washington Wizards’ last three home losses, someone has stood victoriously in the visitors’ locker room and responded to questions about his big scoring night.

On Nov. 1, after back-cutting the Wizards to oblivion and generally outworking every defender for a career-high 40 points, Phoenix Suns forward T.J. Warren proclaimed, “Everything was just falling.”

On Friday, Cleveland’s LeBron James followed his 57-point night, the highest point total scored at Capital One Arena, by turning the Wizards’ defensive effort into a scripted punchline: “I thought I was going to get some double team coming at some point. You know how they say we going to live with it? [shrug] I guess they lived with it.”

By Tuesday, it was Harrison Barnes’s turn after his Dallas Mavericks became the third consecutive visiting opponent to dismantle the Wizards’ defense in a road win. Though he was averaging 17.3 points per game coming in, Barnes hit his midrange looks and worked in the low post and on the left side to score a season-high 31.

“I guess they didn’t think I was a good [isolation] scorer,” Barnes said after the Mavericks’ 113-99 win. “I had to make them pay.”

While three separate opposing players have had reason to beat their chest, the Wizards have searched for answers. Nothing has explained away the lack of defensive effort on their home court.

At the start of the season, Wizards guard Bradley Beal approved of the rechristened arena’s nickname, “The Vault,” saying, “We got to lock up the defense. We got to lock up our house. This is our house.” So much for home security. For three straight losses in Washington, the Wizards have allowed 121.7 points per game and seemingly had no strategic response against a single player on a tear.

“It’s pretty much the same as all our losses,” Beal said. “We didn’t play hard. They outworked us. We didn’t defend. That’s plain and simple. You don’t win if you don’t defend.”

Weary of the Mavericks’ three-point shooters, Washington chose not to double-team Barnes. The team decided to live with his long twos and jump shots. The only problem: Barnes not only had a big night, but the Wizards allowed Wesley Matthews to drill four of the team’s 11 threes and rookie Dennis Smith Jr. to score nine points in the first quarter.

Smith’s barrage continued the troubling trend of bad starts for the Wizards. The Cavaliers scored 42 in the first quarter during their nationally televised game last week. On Tuesday, Dallas, one of the lowest scoring teams in the league, breezed to 36 points through the opening 12 minutes.

While the blame can be passed around the 11 players who checked into the game, most of the responsibility belongs to the scoring-obsessed starters.

When asked about Otto Porter Jr’s efficient night on limited shots (13 points on 5-for-8 shooting), Coach Scott Brooks entertained the inquiry for a moment then added the big “but.”

“I love Otto and what he does, but it’s about defense. Otto needs to be a better defender, just like the rest of the guys,” Brooks said. “Our starters, [Marcin Gortat], [Markieff Morris], [Beal] and John [Wall], they need to start the game off with better defense. It’s not on offense. We scored 34 points first quarter.”

Each starter registered negative plus-minus numbers Tuesday, and the Wizards never held a lead against the 2-10 Mavericks.

It was the type of win that offers a life preserver to a struggling team.

“We will take the win wherever and whenever we get it,” the Mavericks’ Dirk Nowitzki said.

And for the team in the home locker room, this was the kind of loss that begs for personal accountability.

“It’s just a matter of us looking ourselves in the mirror individually and again as a team to see where we want to go, see the things that we’ve accomplished last year and be hungry for it,” Beal said. “We’ve got to get hungry again. I think we’re a great team, but we got to act like a great team and go out there and prove it.”

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