Looks like SDHQ has weighed in on the subject at hand......their stance seems to be that it's caused by abuse.
Posted by SDHQ.....
"There have been quite a few questions in this 40+ page thread about our products.. Here is some info that will hopefully answer them for you.
We have been questioned a few times for not reporting the frame damage to the Raptor community when we first became aware of the damaged frames. I felt like there was no reason to "blow the whistle" on the damage that was done to these trucks that came through our shop. These trucks were driven to the extreme and the owners understood that it was their abuse that caused the damage. We see trucks in our shop weekly that have factory components that are compromised, normally due to abuse, as a shop we repair these flaws and build them better... That's just what we do. These “pre-run” bent frame trucks were bent at the upper bump stop mount and all the trucks were involved in very heavy off road abuse. The worst had about a 3"-4" difference between the front of the bed and the rear of the bed. None of our customers took their truck into Ford to attempt to have them covered under warranty. In these cases they understood it was user abuse and they were willing to pay for the repairs themselves. When they left they had straight frames and our rear hydraulic bumps installed."
Doesn't matter though, most of the guys on the Z will still think it's Ford's fault.