I knew I wasn't Crazy about un-killable mechs

from the comander chain in the mwo forums

Rear Components Damage Transfer Bug [In Testing]

BUG : When rear armor is gone, less damage than should be would be transferred to the front components. And if Arms and side torsos were already destroyed only a fraction of the damage that hit the destroyed component locations would transfer into the center torso.

NOTES : Thanks to the community (http://mwomercs.com/...w-in-this-patch) we were able to track down a pretty major issue. Less damage was being taken in the back essentially what this works out to with explosive weapons. And too much with lasers. We were able to fix the bug quickly once we found it, but it will take a while to see if our weapon balancing was based on bad results.

Right now 4xSRM6 takes 5 alpha strikes to destroy an ATLAS 7-d in the back. It should be two if you use optimal numbers.

You may have seen more than a few mechs walking around all red torso's but were very hard to finish off in the back.

Also this issue has been there since the damage systems initial development.

DURATION : 2h

ESTIMATED PATCH : Mid-Late February