Just my thought, but reading the #4 engine using a crazy amount of fuel, could have exploded, damaging the wing it is attached to, causing (in the blast) the wing to sweep backwards, where the entire wing crumbles the wingbox inbound from behind, then as I see the pictures in the media I see the airplane went into an excessive roll and ended upsidedown, during this excessive roll the front section of the airplane was detached by torque and went down, with the red part in the NTSB drawings cluttered of into smaller pieces.
What I would like to know is how (in what state) and if they have found the #4 engine itself.
All of the rest is just impact forces.
Again just my thoughts.