I really enjoyed listening to your analysis of the Banned and Restricted list announcement, but I think that by focusing on the empirical results you missed out on discussing what is in my opinion the key point of why many such as myself wanted Gush to be restricted rather than Lodestone Golem. I certainly cannot think of a way to quantify or prove this, but I think that the power of Gush led to the rise of Workshop decks in the online metagame.
I think that Gush aggro decks forced the blue decks in the field to adapt by homogenizing. Steve, you of all people should be aware of the power of the Gush aggro decks like Mentor or Delver against traditional "Big Blue" decks like Grixis. Gush decks are able to play fewer mana sources and generate card velocity in ways in which you have described in far greater detail than I am capable, which results in them being able to naturally predate the slower control decks.
Correct me if I'm wrong, but I think that despite Workshops performing the best on Magic Online, that Blue decks as a whole were the most popular archetype, if you aggregate all of the Force of Will decks together. When a deck like Delver or Mentor has a favorable matchup against non-Gush aggro decks and seemingly a 50/50 matchup against other Gush aggro decks, which combines to the majority of the field, it is hard to choose a blue deck other than Gush Aggro. The exception to this is Oath, which has a strong Gush matchup, resulting in its success at the last 2 Vintage Championships.
The problem with Gush Aggro thwarting most of the other blue decks and after a point in time almost invalidating them is that the Gush Aggro decks homogenize the format to the point where there is little strategic diversity aside from Mentor vs. Delver/Pyromancer as Gush has monopolized the blue "market" and pushed out other strategies. This homogenization made it significantly easier to build a Workshop deck that was strong in the field. Gush Aggro decks typically don't play as many mana sources as other blue decks, do not win particularly quickly (until they play Mentor) and rely on cantrips to filter cards. A deck like Ravager Workshops lines up perfectly against this, by playing numerous Sphere effects which pressures the mana base of Gush Aggro decks and plays proactive threats which make spending turns casting overpriced cantrips or Gushes hurt more as the deck can win the game relatively quickly, especially when Triskelion is factored into the equation. Ravager Workshops is not nearly as well suited to face something like traditional Grixis control because it has trouble racing or answering something like Tinker, especially when accelerated by fast mana, but it doesn't need to because Gush Aggro has for the most part pushed Grixis from the metagame in the post Dig, post Chalice metagame.
If Gush were restricted I think that decks like Grixis, BUG Fish (not Big Blue, but weak against Gush Aggro), Merfolk and Landstill would reemerge as viable choices in the metagame. Gush Aggro would not disappear, it would diminish in popularity and have to adapt, but there are a myriad of ways to replace Gush, especially in decks which either didn't play 4 Gush before, or were not playing a full compliment of Preordains or the like. Also, the rise of non-Gush Aggro decks would strengthen something like Mentor and Delver as matchups which were at least historically favorable would become more popular. Most importantly, I think that this diversification of Blue decks would force the Workshop decks to change. The cards which are best against Gush Aggro are not the same as those which are best against the "Big Blue" decks, which cuts back on the power level of the Workshop decks.
Perhaps this would not have been enough to weaken Lodestone, but I think it might have balanced the format more than restricting Lodestone Golem.
I completely agree with your opinion that one card should be restricted at a time, Steve. I think any more than one card and the lines between correlation and causation become blurred and you cannot see what is really driving the results.
Also, Steve, I think that your take on the diversity of the Workshop archetype somewhat glossed over the strategic diversity of the pillar. While I do not disagree that a lot of paths which were previously not worth exploring are now more viable which will lead to diversity, I do not think that the pillar lacked decks that took different paths to arrive at the same goals.
For instance, a deck like Terra Nova which relied on 4 Mishra's Factory, 4 Mutavault, Null Rods and a full compliment of Sphere effects operates much differently than Espresso Stax did which used Smokestack and Crucible of Worlds to create a permanent advantage. Terra Nova's goal was to simply put as many Sphere effects onto the board as quickly as possible, something which all Workshop decks can achieve, but which this one was built to do because it played 4 Phyrexian Metamorph and up to 2 Sculpting Steels. These decks occupy the true Control end of the spectrum, whereas the Martello (Forgemaster) decks play more of a combo role. Although both Smokestack and Kuldotha Forgemaster lead to the same end goal in a somewhat similar fashion - not doing anything the turn they come into play, the means to the end is much different. Forgemaster decks play numerous targets to tutor up which answer opposing threats, rather than something which kills indiscriminately like Smokestack. Then in the aggro corner you have the Ravager Workshop decks which feature more creatures and try to play more of a tempo game in which they slow the opponent down enough that they can get in 20 damage, rather than relying on locking the opponent out from ever casting another spell as the Terra Nova, Espresso and Martello decks do (Martello does this list than Espresso or Terra Nova because you can tutor up a big creature like Sundering Titan to do this).
While this may seem like minor variations in some instances, the differences between these decks is similar to the strategic diversity that blue decks face where they may play 40-50 of the same cards, but have a different win condition, like say 4 Oath of Druids, 3 Griselbrand 3 Show and Tell, 4 Forbidden Orchard compared to 3 Snapcaster Mage 1 Tinker, 1 Blightsteel Colossus, 4 Gush and 5 other cards.