I think the question is what kind of ratings ESPN thinks it might get from UVA fans, and some of that may depend on how UVA looks in their opening game. The question isn't how many UVA fans will not watch a late game in the East, the real question is how BYU-UVA stacks up, in terms of expected ratings, versus the other ESPN games that are selected for that day. The issue will be with games with two east coast teams, where you lose large portions of both fan bases in a later slot.

Of course, the other issue is that some conferences "own" certain time slots. For example, I believe the Big 10 "owns" one of the ESPN noon ET slots, I believe the ACC also "owns" at least one Saturday noon/3:30 slot, etc. In reality, there are only a couple of open slots during the day on ESPN networks and the BYU-UVA would need to be expected to provide better ratings than the other games selected for open slots.