Mixed martial arts is a sport of ridiculously fine margins.
Unless their name is Conor McGregor (who's seemingly free to commit all manner of offences without the UFC's reprimand), a fighter's place is never truly secure. Inside the Octagon, a matter of millimetres can mean the difference between knockout punch or glancing blow, tapping out or slipping out, and even after the closing bell tolls, a single error of judgment can see a competitor backlisted.
Sometimes, none of this even matters. Dana White can end a fighter's UFC career with a click of his fingers. We saw it last week, when hot prospect Yair Rodriguez was cut for turning a fight down, and in April, when the promotion effectively bought out the last bout on Leslie Smith's contract. Releases and retirements usually come from a place of logic, though, and they often stem from a single moment.
Including anything billed as a retirement fight would be cheap, so they're excluded. The same goes for incidents that happened away from the Octagon itself, like the aforementioned Smith/Rodriguez situations.
With that in mind, let's dive into the defeats, disgraces, and dumb decisions that spelled the end for these fighters...