The Pacers' Pascal Siakam goes to the basket against the...

The Pacers' Pascal Siakam goes to the basket against the Nets' Nic Claxton during the second half of an NBA game Monday in Indianapolis. Credit: AP/Darron Cummings

INDIANAPOLIS — The Nets proved a maxim true: Those who don’t learn from history are doomed to repeat it.

Just over two weeks ago against the Pacers, the Nets showed no resistance at the rim and repeatedly allowed easy baskets at Gainbridge Fieldhouse. It happened again Monday as the Pacers drove to the basket and parked in the paint.

The Nets again had no answers in their 133-111 loss. They didn’t give up 82 paint points, as they had on March 16, but they did allow 70. They also played into the Pacers’ hands by allowing them to score in transition, as Indiana had 23 fast-break points to the Nets’ five.

The Nets (29-47), playing on the second night of a back-to-back, trailed 75-48 at halftime, the second-most points they’ve allowed in a first half this season.

“It’s hard to stop them in transition when they’re fast-breaking and getting back,” interim coach Kevin Ollie said. “But we got to have more sense of urgency getting back, sending everybody back and then getting them in a half court.”

The teams will meet for the third time this season on Wednesday at Barclays Center, the first on the Nets’ home court. It will be a last stand of sorts for their minuscule play-in tournament hopes.

With the Hawks beating the Bulls on Monday, Atlanta’s magic number for clinching the last play-in spot is one. If the Hawks beat the Pistons on Wednesday or the Nets lose, the Nets will be eliminated from postseason contention.

But that’s just a formality, given how the Nets have looked most of the season. They’ve shown inconsistent fight and been outclassed by better teams. The Pacers (43-33) were the latest to expose them.

The Nets took a 4-0 lead, but the Pacers scored the next 15 points. It was eerily similar to Sunday, when the Nets gave up a 17-0 opening run to the Lakers.

“They hit us in the mouth early, got going in transition, got some vibes,” Trendon Watford said. “Hali got going. He started out 0-for-5 last game, so we knew that wasn’t going to happen again.”

Hali is Pacers All-Star guard Tyrese Haliburton. He finished with 27 points and 13 assists despite playing only three quarters.

Six Pacers scored in double figures. Cam Thomas had 22 points to lead the Nets but struggled with three fouls in the first half along with a technical foul.

After the technical foul, Thomas bent over in frustration. Mikal Bridges walked behind him to pat him on the back and encourage him.

There was an embarrassing second-quarter sequence following a made basket by Pacers center Jalen Smith. Smith was fouled and missed the free throw, but the Nets forgot it was a live ball. Jarace Walker, who wasn’t boxed out, walked in the paint and grabbed the rebound for an easy putback.

It was a mental lapse by a team that trailed by as many as 29 in the second quarter and 36 in the third. Between that, 15 turnovers and allowing the Pacers to run, the Nets fueled the Pacers’ strengths.

Watford had 21 points off the bench and Bridges added 19.

The Nets now head into Wednesday knowing their five-year postseason streak could end at home.

“Just got to clean up,” Bridges said. “We know what they’re going to do. We just got to be better. Transition defense is number one. Getting stops. Just got to be better cleaning that up.”

Notes & quotes: Cam Johnson (left big toe sprain) and Dennis Smith Jr. (right hip soreness) were out. They’ve missed four of the last five games. Ollie had no update on their status for Wednesday’s game.

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