@nedleeds (Sean I assume), I'm cross posting this because I'm not sure which platform (FB, EC, TMD) you are the most responsive.
There is a key point which I'm not sure you tackle properly in this article. To my mind, the increase in the average number of Missteps was directly related to the restriction of Chalice of the Void in September 2015.
Blue decks simply got greedier, much lower on the curve and then everybody got stuck playing 4 MM as a consequence of Chalice's restriction.
Before Chalice's restriction, people were much more conscious about spreading their CMC across the curve. Moreover, cards like Spell Snare, Spell Pierce and Hurkyl's were no brainer main deck back then as it was the best answer to un-restricted Chalice (and versatile/good against the rest of the field).
In a field full of Chalices, MM made absolutely no sense. That's the key point.
Last, in a field without Chalice, I think people felt safe knowing that they could rely on 4MM if needed to keep in check the Ritual decks. I think that when Dark Petition + Cabal Therapy + Probe decks started popping out. Then Xerox really took over the format but by then 4MM was already everywhere. It all started when Chalice got restricted.