Mike Miller has theory about Frank Ntilikina’s Knicks setback

For all of the promising games Frank Ntilikina has turned in this season, Saturday’s loss to the 76ers was one of his more pedestrian.

The Knicks point guard finished with just five points (on 2 of 8 shooting), three rebounds, two turnovers and no assists while playing 16:30 in the 90-87 loss at the Garden.

Ntilikina was playing his second game after missing a pair of games with a sore groin. Interim coach Mike Miller indicated the layoff might have been a factor.

“I thought he played really well on the West Coast trip. Then he was out for two games,” Miller said Sunday after a brief practice. “During that time, he wasn’t able to practice. Then you’ve got to come back and kind of reestablish…