I haven't looked at financials, so I'm totally talking out of my arse here, but I assume based on this that the revenue Blizzard have been pulling in towards the Acti-Bliz entity has been dropping recently, without any changes to costs, and the Activision head honchos have potentially become fed up with always bearing the brunt of any restructures or significant firings in the company.
I imagine the real gist behind this is something like revenue from WoW is dropping, there's no real in-game monetisation in Diablo 3 and the re-release/DLC didn't really move the dial, Hearthstone player numbers are dropping as competition grows, StarCraft 2 wasn't as bit of a success as they'd hoped, Heroes of ththe Storm was an outright disaster, and then whatever is happening in Overwatch.
Hopefully we don't see any reductions in quality from this, but I imagine this is part of the reason we're getting Warcraft 3 Reforged and Diablo Immortal.