All the pro's know what happened.
We do not know what caused three professional pilots to behave like "clowns" (to use someone else's unfortunate term).
To dismiss this as pilot error is to abandon thirty-odd years of Human Factors wisdom that has done a very great deal to promote flying safety [best summarised as "if we don't know why they did that we dont know it can't happen again"] , and to go back to the bad old days of "blame and move on".