Higher O2 is not always a good thing. >60% is hyperoxemic tx and promotes fibrosis via free radical injury. Proning does not improve 30 day survivability, although it does transiently improve oxygenation, so maybe its just enough to get someone on the fence through. Head down is a bad idea in prone or supine ventilation as it causes an increase in WEST Zone three via a restrictive mechanism (abdominal contents reducing thoracic volume). So the notion of draining is not founded.
They showed (what was it?) 7% or 14% increased survival in ICU patients with this Coronavirus in a real-life hospital setting, other things being equal. Theory should FOLLOW data. Mumble harrumph "not well designed" mumble "small sample" mumble "no control group" ...
well, the medics in the thick of this were a bit overwhelmed for that at the moment, IIRC that report came from...Italy.