As I discussed previously about the restructure when Grunwald was gone, the decision process was corrupted by Dolan when he hired Phil.
It was always intended to have a single autonomous president at the knick helm. Dolan paid all that money to have good analysis done then he starphuched it.
Ok, that said, why Phil was made gone? Could be in part he wanted to leave and did not like the job. That contract was a promise and Dolan is a lot of things but except for Larry Brown he has not reneged on a deal.
Still, why?
Most important was Mills finally was able to paint a picture that Phil was scaring away deals, FA's and good will. We don't know the full reason why KP skipped but it was evident that there is a stench in the house and while Phil's zen Triangle was a good thing, it was not receptive to free agents and agents and that means we lose leverage in trade talks, free agents, and coaches. Also, Phil took the melodrama to a public level and while I don't think Phil said anything wrong, he still said it. Why bother?
As for KP, the drama of Phil taking calls was not a bad thing and if some of the deals floated were true ( I doubt they were), they would be good trades to boost long term talant acquisition. Phil the exec was not as flexible as phil the coach and its evident that unless you have leverage you can't force that on players or do business with he rest of the league. Now, if Phil had his own people thru the organization and had for some time the culture might have been set but that never happend. Warkentein, Gabriel, H20 all were still here. Fish rejected it and that did big damage. Yes, I think Fish really hurt Phil. Phil did not read him correct, he was not ready to be head coach as a person.
So in the end I don't think its "Corp. greed" that got mills to spring a coup d'état but it was evident that the team could not move forward and the endless drama right before the draft and free agency was detrimental to the team in both free agency and in the construction of deals. The league would take advantage of Phil and that cannot be allowed. Melo certainly had some trade value and a buy out was asinine! With Phil having final say there was no checks and balances.
This is not to say Phil was entirely wrong, but his removal was more about execution and the lose of leverage that diminishes value in transactions. Dolan messed up, he wrote the check. If mills was instrumental in his ouster it was logical, not egotistical.