Tpad, I'm not offended by the remarks but they are unrealistic as far as an engine surge goes. I had one on a 737 and the thing was banging away like a barn door in a storm. There was, however, certainly no noticeable yaw because the loss of thrust during the actual surges was negligible. The autopilot coped very well with the event and certainly didn't produce the results as described. In diagnosing the problem there was no need to rush and there is nothing in the Boeing manuals that suggests you need to close the thrust lever so quickly that yaw in uncontrollable. We closed the thrust lever slowly and applied rudder because, amazingly, we know the autopilot doesn't do this and, by doing what any reasonable 737 pilots would do (and I certainly include Air NZ pilots in that description) we had no aerobatics as described. The autopilot stayed engaged and we maintained altitude (although started to slow to drift down speed). Again, there's no knee-jerk decisions to shut down the engine because once that thrust lever is closed the surging is reduced to a mere annoyance, if it continues at all (as ours did). So, once again, the dreaded yaw can be anticipated and easily countered by the PF. I have no idea at what stage of the game the Air NZ flight had their problem but mine required a descent as we were above the single-engine cruise altitude. Again, no need for dropping like a stone and/or recovering to the original level, as a quick chat with ATC will sort out that problem.
So, all in all, while I normally like A37575's comments, I think this one is over-the-top and certainly does not describe the actions of a trained 737 crew, even if they were relaxed and not coiled springs.