The Rankings Are a Guide, Not a Ladder
UFC divisional rankings are produced by a vote among a panel of media members rather than calculated from a fixed formula, and the promotion presents them as informational. There is no rule that obliges the champion to face the top contender, no automatic mandatory challenger mechanism of the kind boxing's sanctioning bodies operate, and no penalty for skipping several places. Because the rankings are advisory, they can be simultaneously a reasonable summary of who has been winning and completely non-binding on who gets booked.
This has a second-order effect that gets missed. Since ranking position does not guarantee a fight, it functions mainly as a marketing and negotiating input. A number next to a fighter's name helps sell a bout and strengthens their position on terms, which gives them an incentive to protect it, and that shapes which fights they accept, because a loss to an unranked opponent costs more than the reward for beating one. The advisory list influences behaviour a great deal while binding nobody.
