Want to blame last 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.