I honestly don't think we know what the true average impacts of a strong El Niño and strong La Niña are when we have such a small sample size for both. I took Statistics in the Fall of 2015, and learn that for the sample size to get a reliable normal distribution, the sample size has to be 30 or greater. So far since 1950, we have had only three very strong El Niño events (1982-83, 1997-98, and 2015-16) and only two very strong La Niña events. (1973-76 and 1988-89) That's nowhere near enough to get a reliable average of very strong ENSO impacts.