MAUs is a poor metric since it is just a made up company statistic. It counts a player who logs in once and never again in as the same as a player who no lifes the game. It also combines both WoW and Overwatch numbers in the same MAU, as well as hearthstone (when it was around). So there isn’t much transparency into what MAU really provides.
Below is the quarterly data over two years for Blizzard showing MAUs steadily decreasing (remember WOW + overwatch + hearthstone).
12/31/2020 | 9/30/2020 | 6/30/2020 | 3/31/2020 | 12/31/2019 | 9/30/2019 | 6/30/2019 | 3/31/2019 | 12/31/2018 | 9/30/2018 | 6/30/2018 | 3/31/2018 | 12/31/2017 | 9/30/2017 | |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
MAUs | 29 | 30 | 32 | 32 | 32 | 33 | 32 | 32 | 35 | 37 | 37 | 38 | 40 | 42 |