Just as a one-off example, if deck A is by far more powerful and wins more games than deck B in legend.... but deck A and deck B are played at a similar amount and keep each other in check at ranks 10-20, if we were to change deck A it might have strike a balance in legend but create a large disparity in power level for deck B at ranks 10-20. In reality, there are many more moving pieces than this but this is certainly something that can and does happen when we make changes to any card.

There is so much data that I tend to believe if you try hard enough you can find slices of it that represent whatever opinion you want to have, but that certainly isn't our objective. Looking at the entire player population isn't particularly useful when trying to address one issue because it doesn't actually represent any individual players. The reason to share it is I think to give the context that Hearthstone is wildly different depending at the skill range you are playing at. Making a change for one end of the spectrum can have a positive impact on that group but a negative impact on the other end. It's our responsibility as developers to take all those groups into consideration. To add some context to the situation we are currently in, I've been a bit surprised the aggressive deck population at the top end of ladder has remained so high. Statistically speaking this metagame has very strong correlations to GvG. Mech Mage/Shaman were the strongest decks but had 3-4 weak matchups with decks like Control Warrior that were also fairly successful but played at a lower rate. The decks that beat Mech started showing up at a higher rate and the aggressive mech decks saw a drastic drop in population. Once that happened combo decks like Druid/Warlock started appearing more often and ushered back in some of the original aggressive decks and that eventually led into the next set being released. In theory, the MSoG version of that would have been Pirates --> Reno --> Combo Decks --> Back to a variety of aggressive decks --> Next Set. Unfortunately we've been a bit hung up on the first two steps of that rather than having more natural transitions. This could be for any number of reasons, but I suspect it's because the decks that do beat Shaman feel like their matchups with other archetypes are too weak (whether or not that's true in practice).

In any case, statistics only tell part of the story. Fun > Balance. While those two things obviously have some correlation, it's not always the case. Lots of the frustration I see here in particular is the rate at which we do change things, and it's a worthwhile conversation to have. I think that is something we will definitely dive into discussion about, but I think I've spammed enough on this one comment for now :). Thanks again everyone for the feedback.