PvP damage reduced by 10% in hotfix

The @WarcraftDevs twitter account just posted the following tweet, which is going to be a big deal for all PvP oriented players.

We’ve applied a hotfix that reduces PvP damage by 10% in response to an overall increase in damage since Patch 6.1 launched.

— WarcraftDevs (@WarcraftDevs) March 11, 2015

I admit this seems odd to me. Is it just a case of damage quickly outpacing healing and health in general, or was it a completely unforeseen bump in damage, one assumes potentially from PvE gear or some other gearing issue? One would expect specific nerfs if it was felt that  one class is overpowered in PvP, but a general nerf to all PvP damage implies that it’s not seen as X or Y class simply owning everyone else, but rather all classes outperforming what Blizzard expected. And hotfixing it like this seems like it must have been a fairly large priority.

The hotfix seems to be already live, based on the tweet. No word yet on what specifically prompted the change beyond that overall increase in damage.