safetypee,
I'm not a pilot and don't pretend to be one. I know commincations. That's simply where I come from.
Your description of the deep stall and coming out of it is reasonably clear. I'll add that my understanding of any stall is that you get buffeting. I further understand the aircraft had its CG shifted aft by some amount. (It sounds large to me, but what do I know?)
They were apparently or at least possibly flying into a really nasty set of conditions. Their 0210 position seems to plot to inside the West edge of the most severe of the conditions, if I am interpreting the temperature contours as being of interest relative to the severity of conditions.
Entering that region may have upset the applecart leading to a stall that, due to buffeting from the "rough air" (as pilots often say in announcements to the passengers), they were unable to notice. The arrived, somehow, at a condition that required mitigation by precisely the opposite of what they were doing. This persisted, due to no horizon reference, until they bottomed out of the clouds and got low enough the rain did not obscure vision. At that time recovery would be impossible.
Doesn't recovery with a pilot flying the plane require that the pilot actually be aware that the plane is in a stall condition? How possible is it that the poor fellows simply were not aware of the plane's true flight configuration until too late?
JD-EE trying to learn something that MIGHT explain the plane coming in relatively flat quite close to their last reported position if not behind it.