UFC has always been as good as its biggest stars.
Conor: Is arguably bigger than the UFC now. Calls his own shots. Will not fight as much as he used to, and negotiations with him will be a bitch.
Ronda: LOL.
Jon Jones: Being a gangster as usual. When he's not blowing cocaine or crashing cars into pregnant women, he's getting flagged for steroids. Unreliable.
Brock: Brock's return was botched by Jon Jones being Jon Jones.
Sage and Paige: UFC pushed the hell out of them and invested in them. Turns out both can't fight for shit.
WME have been unlucky in some regard. Even their strategy of milking the profit on a short term basis isn't working out well due to many unforeseen variables.