As everyone is speculating how about this.
AP disconnect in turbulence, aircraft aggressively tossed around in same turbulence, two pilots new to the newly introduced pfd/nd combo option. (previous fits efis...fact). Loss of orientation /scan..unusual attitude followed by loss of control.
I bring this up only as the previous report mentioned the dreaded pilot error.
These 800s were new the pilots may have been still bedding in on the pfd. Overload may have screwed with their scan.
Not being judgemental just thinking back to my first few hrs on the pfd
pr any new scan.