The Caverns Below: Impact of the nerf

This guest article was written by Maria Ilie (Blog). Interested in writing articles? Reach out on Discord!

The Caverns Below has been the most controversial quest from the Journey to Un’Goro expansion. On July 10, Blizzard responded to the demands of the players and announced that it was updating the card text from “Play four minions with the same name” to “Play five minions with the same name”. This meant that the quest would now give a better chance to other slower, control-oriented decks, which it was said to have an unfair advantage over previously.

Was this update impactful or did it not make a significant difference, with cards such as Youthful Brewmaster and Gadgetzan Ferryman circumventing even the new, harder rule? To answer this question, we looked at how players behaved in 2 key periods. The first was a 7-day period before the update (June 11- June 17 2017), and the second was a 7-day period after the update was implemented (16 July- 22 July 2017).

Figure 1: Class usage as a percentage of total games played before and after the update

After the update, the Rogue class was played 2.5 percentage points less than before: over 150,000 games in which users chose other classes. The 2 time periods contain around the same total number of games (only varying by 0.19%), which means this decrease can’t be explained by a seasonal fluctuation in overall gameplay. So, the Rogue class decreased in popularity over the span of a month, but let’s see if this is because of Crystal Core being harder to get or not. By just looking at the Rogue class data, we see that The Caverns Below was used almost 20 times less after the update.

Figure 2: Number of times players included The Caverns Below in their decks when playing Rogue

Now let’s investigate if the card became less powerful after the update. We can do that by analyzing the win rates of the players when they had The Caverns Below in their deck. Besides the sharp decrease in card usage, we can see that players used to win 51% of the time when they had the card in their deck, compared to a mere 37% after the update.

Figure 3: Win rates for games where the players had The Caverns Below in their decks

Dividing by region, we can see that the change in win percentage rates varies slightly across the 4 major HearthStone regions. China seems to be the most impacted by the update, with a 16.5 percentage points decrease.

Figure 4: Win rates for games where the players had The Caverns Below in their decks, divided by region

To sum up, the update has definitely had an impact on the power of the card, as well as its popularity. As the Knights of the Frozen Throne is coming up soon, we’ll have to see what new cards will capture the attention of the players.


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"Definitely had an impact on the power of the card" No shit, who would have thought? It would have been much more interesting how it affected the rest of the meta - what did people play instead, did control decks become better or more prominent?