According to the instructed pilot, this was a training flight for a complex airplane endorsement. He reported that he had a total of 17 hours in this make and model airplane and flew with the certificated flight instructor (CFI), who provided instruction, for 13.8 of those hours. The instructed pilot reported that on short final, he informed the CFI that he did not feel comfortable landing on the narrow airstrip, and asserted that he positively transferred the flight controls to the CFI who flew the approach. The CFI reported that during approach, the instructed pilot was the pilot flying. He recalled that the final leg of the approach was shallow, and he instructed the pilot to add power, and hold off on the application of full flaps. He recalled that when the airspeed was 85 knots, he instructed the pilot to close the throttle and hold the flare in order to bleed off airspeed prior to touching down. The CFI reported that the instructed pilot failed to close the throttle and the airplane ballooned about 10 feet during the flare, after which he took control of the airplane and landed. He recalled that when the nose gear touched down, the airplane veered to the right, and he applied left rudder. The CFI affirmed that the instructed pilot told him that he applied pressure to the left rudder pedal also. The airplane exited the runway to the right and came to a rest in a ditch about three feet from the runway. The airplane sustained substantial damage to the firewall and the left wing spar. The pilots reported that there were no mechanical failures or anomalies with the airplane prior to or during the flight that would have prevented normal flight operation.