Deron Williams returned to New York last night — Manhattan, not Brooklyn — and showed the good things that were mostly missing during his time with the Nets.

Williams scored 20 points and had seven assists as the Mavericks beat the Knicks, 104-97, at the Garden.

Williams won’t make his return to Brooklyn until Dec. 23. It’s safe to say he’ll feel pretty good if he plays as well then as he did last night.

“Expectations were high,” Williams said of his time with the Nets, which ended in July when the team waived him as part of a $25-million buyout settlement. “I was injured pretty much the whole time I was there. Four coaches in three and a half years doesn’t help as a point guard for chemistry and things like that. It was constant change. Didn’t work out.

“Never went well, I don’t think. It felt like everybody thought I was the problem. Now I’m gone. I’m excited to be part of another organization where I feel like I’m better suited. I feel like they need a point guard like me a little better here and I’m able to flourish and have the ball in my hands a little bit more. It’s been great for me, it’s been great for my family. It’s a lot more positivity in Dallas and I think I needed that in my life.”

The Nets never reached the heights they were shooting for after acquiring Williams from Utah and the franchise has fallen into disrepair. Williams’ new team is 13-9, but he passed up the opportunity to gloat.

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“There’s nothing you can do,” Williams said. “It’s over. I’m past all that. I’m on to a new chapter. I wish things would have happened differently. But they didn’t. Can’t dwell on it. Just move forward and I think that’s what I’ve done. No regrets, man. Can’t think like that. See y’all December whatever.”

Williams’ fine play this season might be a surprise to some, but Dallas coach Rick Carlisle said he expected as much.

“I expected him to play great and he has,” Carlisle said. “He’s a great player. The things that he’s battled the last couple years have been health issues. Double ankle surgery two years ago. Other nagging injuries. He’s worked extremely hard to push through those things and get himself on the uptick. You always knock on wood with things like that, but hard work is paying off for him.”

Williams started alongside former Knick Raymond Felton in Dallas’ all-point guard backcourt. Felton had 14 points and five assists. The Knicks’ starting backcourt of Arron Afflalo and Jose Calderon combined for 20 points and nine assists.