Most likely the crew could not overcome the stab authority any more, in DC8 times known as "jackknifing".
If as a result the crooked negative camber of the stab/elev position, it might have stalled completely.
Similar to a plane that looses its complete stab, and we all know what happens then, don't we? With the CG in front of the Lift vector, the fuse will rotate DOWN. FAST.
A dramatic video about this phenomenon can be seen with the demise of some poor helpless chaps, note the wings indicating a dramatic "negative G"