That's the point - there doesn't have to be anyone nearby. If the QB gets outside the tackle box, and throws it past the line of scrimmage, it's not intentional grounding, even if no receiver is in the neighborhood.
I love how the commentators have to justify every single James Harrison hit and tell us if it was legal or not.
Well the Ravens were 5-0 at home going into this game...anyone know the other AFC team that''s 5-0 at home going into Week 13?