The "real issues" here are readily apparent and surprisingly simple...
1) the PF completely failed in following SOP for the event. Instead of flying pitch and power when confronted with unreliable airspeed he commanded the aircraft to climb. Beyond that initial failure he maintained maximum control surface deflection (full back stick) for most of the descent.
2) The PM failed to exercise command authority even though he was the senior pilot on the flight deck and was well aware that the PF was not handling the situation correctly.
3) The Captain did not assume command upon return the the flight deck in any meaningful way.