Rules?
How about anomalies instead. I would speculate that it is not programmed to happen that what looks like a hit isn't a hit.
It's another mystery of the internet vs. "It's Hitech's fault".
wrongway
Is anyone applying blame or are we trying to figure out "the mystery"?
Consider that HTC has a bugs forum (this thread is linked to in there) encouraging players to come forward with evidence of problems. They take that evidence, examine, and determine if it's a problem that can be fixed. Read over the last few update logs. Reporting bugs helps the progression of the game. Ignoring it and pretending everything is fine, is stagnation and allows no growth. If this were an arcade game fine, but the powers that be have invested large amounts of time and money into making their product as accurate as possible while still balancing game play. This does not seem to be an issue of balancing though.
Consider the statements made by HTC on the effects of lag vs damage and how they contradict the "anomalies" in the films.
Consider we're seeking a solid answer and not speculation.
I really don't understand why examining what a large population of players consider a bug is bad.