If they became visual what caused the undershoot? Back in the day a VC8 touched down on the grass to the left of the RWY. (All 3 u/c) snaked about a bit till it got back on the hard surface. Well neither pilot could explain why they had let the aircraft touch down in that position only mitigation was they saw the RWY late. (250’) something within humans that despite what they are seeing they see what they want to see.