The author, dmor, is not familiar with the semantics of the Alexa rank. Nor are most readers. We know loosely that low rank is good. But what does going from rank 1000 to 100 really mean? How hard is that? Is it a traffic increase of 10x? 100x? What exponential base does it follow?
So this chart shows the YC companies that have the largest Alexa rank delta. Frankly, the rankings look plain wrong to me, based upon what I know of these companies.
Other commentators have suggested that, given the power law distribution, we actually care about the delta log-rank. A priori, I would agree. But then we get a new ranked list, and we still don't know if we're actually learning something or our log-metric is messed up. That's actually quite pernicious, if the results look vaguely correct at a coarse level, so we trust the results at a fine-grained level, and don't realize that the methodology and results are wrong.
We're all just blowing hot air because we don't really know what Alexa ranks mean. Only SEOs who work with Alexa ranks frequently, understand the undocumented warts, and have a gut sense of what they mean, can interpret this.
But right now, we really have no point of reference and the table leaves us without having gained any insight.
Perhaps I'm actually happy that the results are so clearly wrong and not helpful. At least that way, no one will trust them. It would be much more insidious if the results were commonly thought to be instructive, but in fact were misleading.