It has always been my impression that MWO uses isolated Directional Damage, this is why we have independent front and back armor. However, though rare in the grand scheme of things, many times over the couple years I've been around I've seen damage apparently apply to the wrong locations. Most recent examples I took screenshots of almost as soon as it happened (within a second or two). The seeming rarity of the event would make trying to record video of it impractical even I could.
This one just happened earlier tonight:
Spoiler
If you notice my position, it's forward of where I was when the actual shot landed (I was on the ramp behind me at the time, directly opposite of where they were entering the caldera). I saw the shot fired, from the Atlas on the right (probably an AC20 shell). I was facing it head on when the shot was fired, lasers grazed my right arm and torso at roughly the same time. Now somehow, despite being face on with the target, the shell impacted my left rear torso armor with no damage anywhere else, simultaneously the lasers somehow managed to deal damage to my right rear torso again despite being head on (I was not twisting when the shots impacted, and received no additional fire). Even if I hadn't seen the shot fired, there were no teammates in position to have put fire into my back, so it can't be friendly fire.
Another example from awhile ago:
Spoiler
In this one, again damage was somehow dealt to my rear side torso armor and nowhere else, once again despite being face on to where fire was comming from, and again no friendly fire would have been possible for this type of damage.
So I must ask, does MWO use isolated directional damage - as I always assumed it does - or is there some damage distribution done between front and back armor? Is it just a bug? An odd fluke of latency? A quirk of hitboxes? a magic bullet fired from the grassy knoll? Thoughts?