Activision Blizzard will no longer report World of Warcraft subscription numbers, the company announced in its quarterly earnings call today.

The current base of WOW subscribers sits at a ten-year low of 5.5 million, down 100,000 or so from the last quarter and significantly lower than its peak of 12 million in 2010.

Company representatives said of the figure, "Note that this is the last quarter that we plan to provide subscriber numbers. There are other metrics that are better indicators of the overall Blizzard business performance."

No indication was given of what engagement metrics Activision Blizzard plans to use.

Clues may lie in its vague reporting of other games' engagement, however.

The company reported that Hearthstone was up 77 percent in unspecified "key engagement metrics," and the game set a quarterly revenue record.

Meanwhile, Destiny was reported to have 25 million registered players playing an average of 3 hours a day, while Skylanders' "toys-per-player number" was reported as up over last year.

The next World of Warcraft expansion, Legion, is likely to launch next year.