something must have gone seriously wrong for the nose of the plane to have declined at such an extreme angle.
"You need something to hold the nose down” said Benjamin Berman, a a former NTSB investigator who has experience flying 737s.
Aviation Experts Baffled By Crash Of China Eastern Airlines Flight MU5735
Possible. But the descent airspeed (all be it the GS from the flight radar data) seems controlled. More like a rapid descent (although extreme) at around 6000 fpm.