Hmm... Maybe that is the secret.
One story that always stuck in my head talking to a guy that flew over Vietnam was, they jinked every 2 or 3 seconds when they were over AA. If you flew straight any longer, the guy had enough time to sight on you, and for the round to get there.
Thinking about that for a second, it occurred to me that if that was the case, any round that actually hit you was technically a 'miss', because if he was aiming along your vector before you jinked, and it hit you after you jinked it was because it didn't hit where he was aiming.
Maybe it's because the puffy ack is programmed to theoretically miss the fighter, because he's maneuvering he flies into it...
Wiley.