I'm not an adcom, so please bear that in mind, but the way it was described to me by those who know, ALL schools yield protect. Internally, they refer to it as resource management.
The rationale is not to punish anyone whose application is deemed to be too strong for the school. Rather, it's a concession to the reality that there are only so many interview slots, and it's a waste of limited resources to allocate them to applicants empirically unlikely to attend, based on reams of prior cycle data.
Hopefully @REL will provide a more informative, specific response with respect to UCF, but that's my understanding.