Daniel, Any behavior or pattern that looks complex but that you can describe with a short algorithm is an example of negative entropy (or low entropy). So if a model of ENSO can be described with a short algorithm then conceivably the mechanism underlying ENSO is a low entropy, ordered behavior.
How short is the algorithm for describing tides? The example below is based on a very short low entropy algorithm, based on the astronomical factors, and explains essentially everything except for obvious storm surge signal spike in the middle.
So we take that SAME set of astronomical factors using the data from [NASA JPL ephemeris](https://ssd.jpl.nasa.gov/?horizons) or [an astronomical algorithm](https://www.sciencedirect.com/science/article/pii/B9780128205136000229) and we can get this for ENSO by applying [Laplace's Tidal Equations](https://en.wikipedia.org/wiki/Theory_of_tides#Laplace's_tidal_equations):
So we can conclude that ENSO is not a very complex system since it can be described succinctly.
But if anyone wants to debunk it or reject the model with their own better low entropy model then they can go ahead and try.