For two and a half quarters, it looked as though the Boston Celtics were going to reject the spectacle of this year’s highest-profile regular season matchup wholesale. With the 15-0 Cleveland Cavaliers in town, the defending champs appeared to be back to their old tricks of yesteryear, making fools out of an Eastern Conference hopeful once again. When they took a game-high 21-point lead over the Cleveland Cavaliers in the early minutes of the third quarter, you’d be forgiven for wondering which of these two teams was actually the undefeated one. The Celtics were in complete control.