Henra, I admit I am out on a limb here with saw in hand. My understanding is that the recovery technique for a stall is to get the nose down, gain airspeed, and then do something about that solid object towards which you are not headed at an absurd speed. What I'm proposing is that they were at that last stage with too little height to finish the pull-up or even finish a ditch scenario.
I admit this is a reach. It's one way to come close to reconciling a set of data that seems to be utter nonsense. That it requires an "interesting" coincidence of events indicates it's not one of the more likely candidates.
(Another thing the data and discussions have raised in my head is the absurd image if a tail mounted rocket pointed straight down with the intent of getting a plane out of a flat "spin" or sink into which it "supposedly" cannot get into. Sometimes my mind goes "out there". That usually happens when I get tired and start feeling whimsical. I try not to discard even the absurd ideas. That's how I got the one patent in my name, I'd noticed a phenomenon that was irritating in one set of data I was taking. As it happened it applied well to creating an ultra-low powered SatCom transmitter for somebody who shall remain nameless. I am unreasonably proud of that patent, though.)