BOSTON — The Knicks are becoming consistent, and not in a good way — another game, another double-digit deficit and another loss.

This time it was the Celtics who outplayed the Knicks and recorded a 100-91 win Sunday night. The Knicks have dropped four straight and needed a big scoring night from Carmelo Anthony just to be in this game.

The Knicks trailed by 15 in the third quarter and 14 in the fourth before making a run to get within five. But they missed four consecutive shots and never got closer. The Knicks fell to 14-18 on the season.

Anthony scored a game-high 29 points and grabbed 10 rebounds, but he was 11-for-26 from the field. Kristaps Porzingis didn’t shoot the ball well again. He was 4-for-13, but finished with his 12th double-double of the season: 16 points and 12 rebounds.

“Execution wasn’t perfect but we had some good looks,” Derek fisher said. “We stayed together. Our defense hung in there. We showed more resolve tonight but still not good enough.”

Isaiah Thomas led Boston (18-13) with 21 points, including eight of the Celtics’ last 10. He also had eight rebounds and six assists. Evan Turner added 19 and Jae Crowder 18.

The Knicks were down 83-69 less than two minutes into the fourth quarter. They cut the deficit in half less than three minutes later after five consecutive points by Derrick Williams made it 85-78 with 7:14 left.

Later, Anthony drilled a three-pointer that narrowed the gap to 88-83 with 5:30 to go, the closest the Knicks had been since the second quarter. Two Porzingis free throws with 4:48 left kept the Knicks within five at 90-85.

They had three opportunities to draw closer, but Porzingis misfired on two attempts and Langston Galloway bricked a three-pointer.

Thomas then scored inside to make it 92-85 with 2:59 left. Following a missed three-pointer by Arron Afflalo, Thomas scored in transition to give Boston a nine-point lead with 2:40 remaining.

The Knicks still had a little life left, down 96-89 with under 1:40 remaining. But Anthony missed two three-pointers and Thomas sealed the game with two foul shots with 50.9 seconds to go on a trip when Boston came up with two offensive rebounds.

The Knicks are in a part of the schedule when they play 10 of 11 games against playoff teams from a season ago. After dropping the first two, Anthony said this stretch “could define” the Knicks, and that they’ve “got to want it more.”

Fisher liked that Anthony said that.

“The players are the ones that have to make the plays,” Fisher said. “We can create game plans, strategies, coverages, et cetera, but when the game starts it’s really those guys that have to get it done. Anything we want to accomplish has to start and end with them.

“I think we’re making progress. But you play against really good teams you have to embrace that. And that’s where you learn about how difficult it is to win and all the little detail things it takes to get there.”

But the Knicks didn’t start this game off like they wanted it more than the Celtics. The Knicks shot 7-for-26 in the first quarter, scored 18 points and didn’t hustle after loose balls or rebounds with as much passion as Boston.

Things worsened for the Knicks in the second. They were outscored 25-11 during a 7:12 span in the quarter as Boston opened up a 47-33 lead. Anthony scored the Knicks’ last six points of the half, helping to keep them within striking distance.

Anthony, who scored 14 points on 15 first-half shots, buried a baseline jumper with 6.1 seconds to go in the half that made it 51-41. But that momentum didn’t carry over to the third quarter.

The Knicks played sloppy basketball. They committed six turnovers and scored just one field goal in the first 4:48 and fell behind 59-44. The Knicks made a little run to get within 61-53, but turnovers continued to bedevil them. They ended the quarter with eight and in a 77-65 hole.