NBA

Home groans: Nets drop 3rd straight at Barclays Center

Want to blame Friday night’s Nets loss to the Mavericks on something missing from their game? Take your pick.

No defense, little energy, careless turnovers — all of them could be used to describe an ugly 98-90 loss to the Mavericks, the Nets’ third defeat in their last four games and third straight at home.

“We’re not winning,” Deron Williams said. “We’ve lost three straight [at home]. … That’s what I’m most concerned with.

“We keep talking about protecting home court, and we haven’t. That’s the thing that’s most alarming me.”

The Nets allowed Dallas to shoot 50 percent from the field, including hitting nine 3-pointers. The Nets also committed 20 turnovers that led to 17 Mavericks points and looked lifeless during a third quarter that saw them outscored 29-14. The Nets fell behind by as many as 20 points in the fourth quarter before a late comeback made the final score closer than the game indicated.

Many of the Nets’ problems stemmed from turnovers. That began with Williams, who grew up in the Dallas area, was facing the Mavericks for the first time since he spurned them and chose to re-sign with the Nets last summer.

Though Williams continued his impressive offensive output since the All-Star break, scoring 24 points on 8-for-18 shooting, he committed seven of the Nets’ 20 turnovers.

“It started with me, and then I think it had a snowball effect,” Williams said. “I was throwing the ball everywhere. It’s one of those things where you see a guy making a bad pass, and you start thinking about it.

“I know I was thinking about it. … We were trying to make good things happen, but they were deflecting the passes and making us pay.”

The lack of energy — something the Nets have often cited after losses this season — was an obvious problem at the start, and on the defensive end in particular, where they allowed the Mavericks to get plenty of wide-open looks.

“One through 12, we didn’t have any energy,” said Brook Lopez, who finished with 19 points, nine rebounds and a blocked shot. “There was no energy on the floor, and no energy on the bench.”

The only reason the Nets held a 49-48 halftime lead was because Dallas was matching them in the porous defense category. The Nets shot just under 54 percent from the field.

It didn’t get much better after the break, as Dirk Nowitzki and Vince Carter each finished with 20 points to lead the Mavericks, while O.J. Mayo added 17, and each member of the trio shot at least 50 percent from the floor.

“I thought both teams weren’t stopping each other,” Nets interim coach P.J. Carlesimo said. “[It was] like an old-time ABA game. That’s disrespectful to the ABA, but nobody was stopping anybody.

“It was going to be like if somebody decided to play defense for five minutes they were going to win the game.”

That turned out to be the Mavericks, who turned the screws on the Nets in the third, the quarter that has cost the Nets countless times this season. They not only forced the Nets into shooting 5-for-17 from the field, but also into four turnovers that led to five Mavericks points.

Dallas ended the quarter with a 14-4 run, which was capped by a Shawn Marion blocking Mirza Teletovic’s 3-point attempt and then racing out to catch a full-court baseball pass from Vince Carter for a dunk as the quarter ended.

“[The third quarter] has been an on-going thing the whole year,” said Joe Johnson, who finished with 11 points and six assists in 29 minutes in his first game back after missing three with a sore left heel. “We talked about it after the game, and hopefully we can come out in Chicago [tonight] with a better effort.”

If they want a win in the Windy City, they will need one.

tbontemps@nypost.com