So there's nothing to say that our purported Pouncing Proavis is either hunting alone *or* directly pouncing on prey.
I should have thought of the first point!
Maybe small family groups are using pouncing to get down from lookout positions all *around* prey, greatly increasing their collective chances of making the capture without trying to do the direct, modern, hawk-pounce on it. [...] Pouncing wouldn't even have to be particularly *close* to prey for that to work; it would just have to provide a modest improvement to the odds of prey capture.