Just as the Boston Celtics are finally reaching the culmination of their rebuild, the Eastern Conference is the weakest it has been in recent memory. The Celtics are the only team that can be put in the top tier of teams in the NBA, and no one else is really doing anything to catch up to them.
With LeBron James gone, and no other significant player coming back, the East is the most wide open it has been for this generation. Op top of that, the Celtics clearly gave James the best competition in the East, before adding two of the best players in the entire conference.