What notable booboos has he done?
The biggest ones .....
He mandates that his head-coaches (Fisher, Rambks & Hornacek) exclusively run the triangle offense, which looks lost in todays fast-paced NBA ....... as Reggie Miller, Charles Barkley, etc and a few other legends playfully say ~ the triangle offense only works if you have a Michael Jordan, Kobe, Shaq, etc.
Questionable transactions ....... He has traded nice role players (JR Smith, Shumoert, Chandler, etc) for little in return. Had given an albatross contract to an injured Noah and had resigned and even gave a no-trade clause to Melo.
Totally alienated his star player Melo, diminishing any leverage that he had for any potential trade ........ I'm in no way a fan of Carmelo (I dont think anyone is), but Melo did not deserve the tratement that he got from Phil Jackson. Heck, even Porzingis didn't agree and didn't bother to attend his exit interview.
When even Scottie Pippen says that Phil Jackson needs to get fired, that says a lot.