Still, behind closed doors in the Celtics training facility in Waltham, there was disappointment. But there was no cursing Isaiah Thomas for being in the lottery room in New York and not bringing home the big prize. “There were some groans. I think the buildup, once we weren’t sixth and we weren’t five and we weren’t four, there was a lot of hope that we could get a good pick,” Ainge said. “But we’ll take it. We’ll give Isaiah a passing grade. We’ll keep him.”