Shaking things up
The most reasonable explanation for Blizzard’s actions is best found in the previous mid-expansion update. Back on the 18th of September, they stated outright that they were “happy with the excellent diversity of decks”, and thus weren’t looking to make too many urgent changes.
Instead, I believe that by changing Giggling Inventor and Mana Wyrm, Blizzard wasn’t intending to massively re-balance the meta away from a certain strategy or archetype. Instead, they were simply seeking to change things up enough to keep it fresh.
Though it’s hard to track exactly, a number of community metrics report a significant decline in average player-base for this point in an expansion’s release schedule. This, more than any meta considerations, may be the rationale behind the decision.
Druid: Too big to fail?
Druid today makes up a giant proportion of the meta. At many ranks, various Druid decks constitute more than a fifth of all games. And since almost all of them rely on the same 18-24 card spell core, it would be a massive risk to change them. If you nerf a key card and the whole package becomes untenable, it could lead to massive destabilization away from what Blizzard ultimately sees as a healthy meta.
While many would argue the benefits would outweigh the risks, it’s worth pointing out that a new expansion is not too far away. In the end, it may be better from Blizzard’s perspective to focus on a small meta shift and save the big changes for the final expansion of the year. Especially considering it’s almost certainly going to be on an extremely high power level.
Why Mana Wyrm?
If Blizzard were fundamentally happy with the state of the meta-game, the question remains; why nerf Mana Wyrm? After all, tempo Mage was arguably a healthy balancer to the likes of Quest Rogue, and by no means an overpowered deck.
Here’s my theory: they were going to rotate Mana Wyrm to the hall of fame anyway. Nerfing Giggling Inventor may not be enough to change the meta significantly, so they needed an additional ‘safe’ and justified nerf that would provide the requisite meta shift. Considering Blizzard’s design pivot away from power 1-drops, Mana Wyrm seems to fit the bill perfectly. This also goes some way to suggest the inelegance of the nerf; as it was originally planned to go unchanged into wild. This is all conjecture, but it may provide some solace to traumatised Mage mains.
Images courtesy of Blizzard Entertainment via hearthstone.gamepedia.com.