Analyzing Hearthstone: How Timing of Cards Played Impact Winrate

Colin McNeil
Jul 24, 2017 · 2 min read

A service called HearthScry publishes anonymous monthly data which users opted in to providing. With 28,577 games to look at, I went to work analyzing it with Pandas in Python. You can find the source below.


Analysis

I started by looking at every ranked game during the month of June and started looking at winrate. I always wondered how drawing certain cards early or late affects player performance. To me, Hearthstone’s card draw variance seems very impactful to each game and is mostly out of control of the players. I set out to determine exactly how much drawing a certain card at a certain time would affect winrate.

Patches the Pirate

To begin, I looked at one of the most infamous cards of aggressive decks: Patches the Pirate. I wrote a Python script to determine winrates of players who played our pirate friend at each turn.

As the chart indicates, patches entering play on turn 1 gives a 56% winrate, and declines each turn after. However, games that lasted until turn 7 or higher had even greater success. Note that after turn 6 sample size (games patches was played) dropped to about 50, and after turn 9 sample size was single digits.

Crystal Core

For the next card, I analyzed the Rogue Quest, Crystal Core. Specifically playing the quest reward. There were 4 lucky players who managed to play the quest on turn 3 in the sample, less than 0.5%. All 4 of those players won. More modestly, playing the quest up to turn 8 yielded a better-than-50% chance to win.

Vicious Fledgling

Besides Crystal Core, another polarizing card in the community is Vicious Fledgling. Specifically, token druids innervating Fledgling on turn 1 is viewed as extremely overpowered. The data shows that while it is strong, it is not as strong as quest rogue before the nerf. Furthermore, playing it after turn 5 hampered winrates. Sample size by turn 11 is below 20. Incredibly, more Fledglings were played on turn 1 than any other turn.

Colin McNeil

Written by

Devotee of all things tech (University of Connecticut — Computer Science)

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