if it wasn't obvious to u already since he got benched last year, here's his explanation for the move...
"It was a business decision and the team put me in the position where we had to move. We had to go. Miami was a better choice for us based on what the team was doing, so it wasn’t, don’t boo me, boo the team in a sense. Now it’s out of my control. … When this contract situation came down, everybody in my circle — mom, family, brother, sister, friends from college, people who watched me since I was in high school and since I was in college — nobody wanted me to resign in that situation because they thought, ‘There [is] so much left in you and this team isn’t taking care of you or treating you right.’ That’s the way I felt and it was like, if you are going to come and not put out a good contract on the table then, hey, we gotta think about going somewhere else.” Interesting. We need to note here that Boston offered Allen more money — Boston offered two years at $6 million per, Miami and he reached a deal for two years at the tax-payers mid-level ($3 million this year, $3.2 next year).
If Boston’s contract was insulting to him in some way, he didn’t make more moving on.
Which shows this wasn’t about money, it was about being wanted. Boston is a team shifting to the future — Rondo will be the man, Avery Bradley is a good fit next to him in the backcourt. Allen felt pushed aside by all that. He goes down to Miami and he is courted and told how much he is wanted and needed and that wins him over. Allen has his money, this was about playing where he felt a fit, where he felt needed.
And it’s natural for him to think Boston didn’t give him that. Even if it doesn’t look like that at all from the Celtics’ side of the table.