Theory: Something jammed/restricted the flight controls in the cockpit  

If during the two barrel rolls things came out of the door pockets and center console storage I could see it being a problem....Ipad, flight manuals, binders for whatever that program has, sometimes a med bag ends up on the floor up front.  But there was about 45 seconds between the aircraft rolling out level at 100-200' and went it hit.  Enough I would think for the pilot to toss items off the collective over the seat next to him.