Strong neutral cards can be very beneficial for the game as they represent high value crafts and excellent build-around opportunities. However if too powerful, they can lead to a lack of class identity and repetitious gameplay. The popularity and strength of neutral cards in Kobolds and Catacombs lead to the game being labeled "Neutral-stone" by some.

In late January, Blizzard announced a set of nerfs to a number neutral cards which had found their way into many decks across multiple classes. These changes are summarized here:

In this article we look at the effect of these nerfs and in particular how the relative play rate of the affected neutral cards have changed. Like we did with our 7.1 analysis, we've analyzed over 200 million card plays in the 4 days before and after the release of patch 10.2 and gathered the cards with the lowest and highest relative play rate after the nerfs.

The end of Neutral-stone

Since most of the cards impacted were neutral, it seems reasonable that the neutral play rate would decrease. The data suggests that prior to Patch 10.2, 32.1% of cards played in all games of Hearthstone were neutral. The play rate of neutrals has since gone down to 25.8%, a significant decrease. It should be noted that these stats do not include Patches the Pirate summons.

The below shows the relative play rates of neutral cards before and after the patch.

Since the changes, Patches the Pirate and Corridor Creeper are seeing around a 15x reduction in play rate which basically means they've been nuked from the meta orbit. Despite not being directly affected, Southsea Deckhand has suffered a similar fate given it's association to Patches. Golakka Crawler is also seeing a lot less play since pirates have become far less impactful. Bonemare is the least affected out of all the nerfed cards, but that might be because it didn't really have as strong a place in the standard pre-nerf meta game.

Big Winners and Losers

As direct changes are made to meta-defining cards, the entire meta shifts resulting in each and every card becoming more or less playable. The image below shows the cards which were most adversely affected by the nerfs.

Perhaps unsurprisingly, Corridor Creeper was hit the hardest. The top half of the list shows the card being cut from Rogue, Hunter, Mage, Druid, Warlock and Priest, reflective of the sheer power of the card previously.

The greatest impact has been in Rogue, which commonly played all of the nerfed neutral cards. The days of Tempo Rogue being a top tier deck, at least in this form, are over. The nerfs appear to have addressed the power level of Prince Keleseth, which was a point of contention amongst the community. Aggro Druid also appears high on the list, which relied on neutral pirates for token generation as well as cheap Corridor Creeper. Finally, given the direct nerf to Raza the Chained, Highlander Priest has also taken a big hit.

Looking at the cards that have been boosted by the changes, a once forgotten card Potion of Polymorph sits at the top of the heap. You also see cards with silence effects showing up high on the list. Given the incredible power of silence effects on the meta defining Control Warlock and Cube Warlock archetypes, many players are adding multiple silences to their decks. Players are clearly confident in their ability to predict plays from these archetypes, opening up the tantalizing prospect of new forms of counter-play.

Paladin appears to have reverted to the Murloc archetypes which have been strong since Journey to Un'Goro. With the addition of Call to Arms, the deck has risen to the top of the meta. Interestingly, Demons and cards with Demon synergy have also seen a boost, with more aggressive Zoolock varieties becoming more prominent. Hunter secrets are also seeing a resurgence, and Rogue looks to be reverting back to Miracle based decks incorporating Gadgetzan Auctioneer. Finally, Mage has shown some dominance recently with the tempo and secret based decks. A classic, Pyroblast seems to be having renewed impact as players look to bypass big taunts like Voidlord and burst opponents down.

So there you have it. The community response to the nerfs has generally been very positive, and its amazing how positive impact can be achieved by changing only a few cards. The initial concerns of Control Warlocks being overpowered have not come to be, and the data suggest players are testing methods of countering this deck. Its certainly going to be interesting to see who reigns supreme as the meta stabilizes and strategies move away from countering Warlock.