Nets coach Kenny Atkinson spent four years as an assistant in Atlanta, helping Mike Budenholzer coach and the Hawks players develop. But in his first game against his old team, the Hawks didn’t show all that much sentimentality and even less mercy.

On Monday, Budenholzer brought his current staff to Brooklyn to have dinner with Atkinson, and even picked up the check. But 24 hours later, Atkinson’s Nets were getting thrashed 117-97 before 13,279 at Barclays Center.

“Well, you feel a little bit for Kenny Atkinson,’’ Budenholzer said. “Brooklyn is trying to build something special here. The wins are a little bit hard to come by, and you know how hard he’s working and how hard his players are working. It’s hard. I care so much about him, and I want good for him, so it is a little bit hard.”

Though the Hawks (22-16) won their seventh straight game, Atkinson’s Nets were their mirrored reflection, dropping their seventh straight and falling to an NBA-worst 8-29.

“I wish we were a little more competitive. But again, I know I have an intimate knowledge of how they play and the players they have,’’ Atkinson said. “They set the bar high and we can look at it and say someday we’d like to strive to be a similar program. But we have a lot of work to do.”

A Herculean amount.

The Nets were bullied on the boards by Dwight Howard (14 points, 16 rebounds), and with point guard Jeremy Lin still out with a hamstring injury — having missed 25 of their 37 games — they couldn’t handle the Hawks’ traps on the perimeter and couldn’t contain or match Dennis Schroder, who had 19 points and 10 assists.

The Nets handed the Hawks’ 28 points off 18 turnovers, while forcing just a dozen themselves.

Atlanta toyed with the Nets from the start. Howard went to shake Lin’s hand, then pulled his arm back at the last second and dabbed in a lighthearted moment. But there was nothing funny about what Howard did to the Nets on the boards, giving them a beating boxer Floyd Mayweather Jr. — seated courtside across from Atlanta’s bench — would have appreciated.

With Trevor Booker out with a hip injury, the Nets got exposed. Howard had as many offensive boards in the first half (seven) as the Nets entire team. He finished with 16 rebounds while Nets center Brook Lopez — despite a team-high 20 points — grabbed just two, none in the first half when the Nets fell behind.

“They had more energy, especially the first half and they outworked us,” Lopez said. “And the numbers clearly show it.”

Down 37-31 in the second quarter, Brooklyn saw a 15-4 run open the game up. The cushion reached 61-41 on Kent Bazemore’s free throws with 1:40 to play in the first half, and it hit 27 in a second that was extended garbage time.

“They came out a lot more aggressive than we did. When it’s like that when a team basically punches first, you’ve got to be able to punch back, and I don’t think we did that,’’ said Sean Kilpatrick, who finished with 14 points. “They kind of caught us in the second quarter and it was pretty much over after that.”

The Nets trailed 61-43 at the break.

It never got closer than 11 points the rest of the way, 89-78 on a Lopez 3-pointer with 9:44 left, and got as high as 27.

“It’s hard when you’re first getting started,’’ Budenholzer said. “Obviously, we have a vision or a way we want to play. But then, you have to find ways it fits the talent, fits the unique skills of your group and tweak and emphasize different things within that vision. Without Jeremy, the point guard is such a big part of any offense or vision.”