The Celtics enter Saturday’s game with the New Orleans Pelicans on a three-game losing streak, two of those losses to teams with losing records and the loss to Philadelphia without All-Star center Joel Embiid. Still, Ainge isn’t distressed about what is a common NBA skid, and noted injuries as a factor. “I don’t think it’s time to react,” he said. “It’s been a rough stretch but I’m not worried about that.”