You're falling into the gap between directivity and direction. After 200hz it's pretty easy to tell where the sound is coming from, ie left, right, front, back etc, below 100hz it barely matters.
Being able to control directivity and sound having an identifiable source and direction aren't quite the same thing.
Ime if your sub outputs much over 150hz placement becomes much more important in terms of sound field, obviously placement is important for room effects at any frequency, but over 150hz other things increasingly come into play