The difference between "utilized" and "required".
PIO would seem to be the answer, but don't forget that post 2:10:51 the aircraft wasn't within a 'normal' flight envelope.
Worth looking at is the yaw damper, the rudder and the lateral 'g' traces. Once in the 'mush' the aircraft was 'nodding' and rolling/banking in a synchronized manner as well as 'fish tailing'.
Pitch Attitude, Rudder Position and Roll Attitude traces have been overlaid in the second trace in this graphic.