During a huddle in the second half, coach Brad Stevens told his players that, for the first time in several games, they were playing Celtics basketball. Though this was probably obvious to anyone who has watched this conference finals series, it was a powerful statement that spoke to both how much of a departure the Celtics’ recent efforts have been from their ideal selves, and to Boston’s potential to be a two-way monster when the players are confident and aggressive. “He was absolutely right, we didn’t play the way we wanted the whole series,” Theis said. “We didn’t play our defense, we did adjustments and we just went back to our system the way we played all year. Everybody felt comfortable in our system. You could tell in the third quarter everybody was just enjoying being out there.”