WASHINGTON — The Nets picked up their second win of the season Sunday.

Were their victories Pyrrhic, or were they progress?

Brooklyn routed Washington 129-106 before 14,164 at Capital One Arena. They came out to watch a pair of teams tanking for lottery positioning, and saw a Nets team determined to win games, not pingpong balls.

The Nets mounted a 23-4 run that spanned the third and fourth quarters, turning a tenuous one-point cushion into a rare laugher.

“There was a moment in the third quarter [Washington] made a run and that group of the bench made an amazing [run]. They responded,” said Nets coach Jordi Fernández. “You get punched and then you punch back. Those are the moments where you see the growth, and the group comes together.”

The growth is easy to see.

The blowout saw Brooklyn improve to 2-11, the third-worst record in the league — and third seed in the lottery. Both victories came against their prime tanking rivals, with Washington and Indiana now sharing identical 1-12 records.

And while the Wizards dropped their 11th straight, the Nets have won two of their past six, leading by as many as two dozen points and showing improvement on the glass and on defense.

Michael Porter Jr. had a game-high 33 points, nine rebounds and seven assists, finishing a plus-16. Tyrese Martin scored 20 off the bench and was plus-26.

But their work on the boards made the difference.

The Nets came in averaging just 26.7 defensive rebounds, on pace for the worst since 1998-99, per Elias. And their 62.5 defensive rebound percentage was the third lowest in recorded league history, and worst since the 1997-98 Raptors.

The flaw cost them in blowing a 16-point lead in Friday’s loss at Orlando. This time, they outrebounded Washington 44-33, and gave up just three offensive boards.

“It was a point of emphasis…It’s really kind of been a pain, an Achilles heel for us to start the season,” said Nic Claxton, who had 17 points, nine rebounds — seven defensive — and seven assists and four blocks.

Brooklyn assistant Steve Hetzel challenged Claxton before the game, going over video clips for the center to study. It worked.

“[Blocks] definitely gets me going. As soon as I block a shot, it’s like on 2K, my takeover meter goes up, so it makes me want to be even more aggressive on the offensive side and just find a way to get a bucket or get to the free throw line…I know the level I can defend at every night, so I’ve got to go do it.”

Washington center Alex Sarr came in averaging 19.1 points and 8.6 rebounds, but Claxton took up the challenge and helped hold last year’s No. 2 pick to just nine points and three boards.

Claxton drew a fifth foul on Sarr with 8:42 in the third, and the latter fouled out with Brooklyn up by 13 in the fourth.

The Nets held Washington to just 44 percent shooting and blocked eight shots.

With Brooklyn clinging to an 85-84 lead with 2:45 left in the third after a driving floater by Washington’s CJ McCollum (17 points), the Nets closed the quarter with nine unanswered points to spark that game-deciding run.

They held the Wizards to 2-of-12 shooting and three turnovers in that span, and Martin took care of the rest. The guard had the last seven straight points of the third, and a dozen in that extended 23-4 blitz.

Martin’s steal off Kyshawn George (29 points) and running dunk capped the run, putting the Nets up 108-88. The clock read 7:55 left, but this one was over.

“Just sticking to the game plan, being able to get downhill, keep guys in jail, knowing where my shooters are going to be on the weak side,” said Martin. “I was either being able to get to the rim, or I sprayed for Noah [Clowney] twice. So guys being in the right spots and just playing in the flow of the game with confidence.”

It’s a confidence Brooklyn didn’t have earlier this season.