That crashing sound you hear is the Celtics falling off their perch atop the NBA standings. They’ve lost 6 of their last 11 games and are no longer leading the league in winning percentage (even slipping briefly behind the Raptors in the East), defensive rating, or any of the other fun metrics that fans have been gleefully quoting all year.
Much has been said and written about the source of their struggles. A lot can probably be blamed on the heavily loaded December schedule (allowing for time to travel to and from London next month).