Fat-tailed distribution
A fat-tailed distribution is one where a small fraction of outcomes carries almost all of the value, so the average describes nothing that matters.
How it works
In a thin-tailed world results cluster near the middle and planning works, at the price that nothing exceptional can happen. In a fat-tailed one, a handful of attempts return everything and most return nothing, and which is which cannot be known in advance. Creative and brand work behaves this way, while almost every process built around it assumes the tidy proportional world where each unit of spend buys its unit of return. Averaging is then exactly the operation that removes what you were looking for. The talks put the split at roughly ten percent of the work producing most of the value, offered as an observation rather than a measurement.
What it changes for a personal brand
Stop reading your numbers as a per-piece scorecard and read the shape instead. If nothing you published this quarter did dramatically better than your median, that is the finding: not bad luck, but evidence you are producing the safe middle where the outlier cannot occur. Your job is to still be publishing when the rare thing happens.