Basic training used to emphasise the importance of not only recovering from a stall but also to recognise it. As MU99 says, slow speed, high nose att, RoD all give it away. I feel that these guys were disorientated, they had forgotten their basic flying training and were engulfed by the wrong mental model. As a general principle, if an aeroplane does not respond as you expect, reduce the AoA and try again. That's good for anything that you put in the air, fast or slow.