Previous crew encountered same problem and dealt with it safely. Th accident crew had the benefit of that experience (from the write up). They also battled the trim for 6 minutes clearly understanding they had a trim runaway. Why they didn't hit the CUTOUT and why after six minutes they could no longer successfully counteract it, is unknown.
Although I read an article that said they swapped to copilot control immediately preceding the dive.
There were only two pilots that knew precisely what they expected and what was ultimately encountered. Unfortunately, they cannot speak for themselves.
It is presumptuous to suggest they knew of, diagnosed correctly or indeed understood that the likely root cause of their predicament was the MCAS, which from all reports pilots did not know was there.
The pilot and co-pilot’s air data systems and indications are independent. The computed airspeeds are monitored. If there is more than a certain difference between the pilot and co-pilot’s airspeed, and you will get the “IAS DISAGREE” message on the PFD. Which is what the head of the KNKT says occured on at least four different flights of this aircraft.
No pilot (with few notable exceptions) will not fight to save the aircraft. These poor souls did the best they could do. They may well have expected an IASDISAGREE. They may have briefed for it, they may even have had the QRH at hand. No one knows definitively.
What is insidious is the Boeing statement, justifying the lack of information on the MCAS stating that (paraphrased) 'in normal operations the pilots would not know of its existence'.