Probably the real reason Lebron left the East. 
http://www.nba.com/article/2018/08/...rie-irving-ready-boston-celtics-training-camp
Having seen both of their 2017-18 seasons ended prematurely by injury, Celtics stars Kyrie Irving and Gordon Hayward are fully recovered and ready for the start of training camp on Sept. 26.
"I don't want to hype it up too much, but I'm saying that, if our training camp were starting today, that they would be here today going full speed," said Celtics president of basketball operations Danny Ainge, as reported by ESPN. "It's not like they need an extra month. I think that they know they have an extra month so they are sort of pacing themselves. They're playing as if to build up to that opening day of training camp."

http://www.nba.com/article/2018/08/...rie-irving-ready-boston-celtics-training-camp
Having seen both of their 2017-18 seasons ended prematurely by injury, Celtics stars Kyrie Irving and Gordon Hayward are fully recovered and ready for the start of training camp on Sept. 26.
"I don't want to hype it up too much, but I'm saying that, if our training camp were starting today, that they would be here today going full speed," said Celtics president of basketball operations Danny Ainge, as reported by ESPN. "It's not like they need an extra month. I think that they know they have an extra month so they are sort of pacing themselves. They're playing as if to build up to that opening day of training camp."