Also consider this: if the changes are indeed reduction to damage taken, then here are a few things that could happen:

1. The reduction is not significant enough to make a difference so people will still run full slaying to kill things faster.

2. The reduction is so much that tanks receive overheals.

3. The reduction is great enough to make tanks not utilize tank stance at all, since the community will still push for more total damage

4. The community just won't care because doing More damage > taking less damage