SI always do this. None of the models know who's got the cover until the " winner" is taken to a meeting and the cover is revealed to them. This, I think, is usually the day before the cover is released.
Who gets the cover is all down to one picture, really.
Who has taken the " cover shot"?
Hilary might be a rookie, but if she takes a pictures and the SI people look at it and think, " THAT'S our cover" then Hilary's got it.
That's why all of the models have to model their butts off! If they don't, they're no way getting the cover.
Here's to hoping!