Unequivocally a nerf to tanker damage as I believe gauntlet was boosting the size of tanker aoes while they were still enjoying the damage/proc calculations of the base aoe sizes. The increase in aoe size in the patch notes I believe is intended to keep their aoes roughly in the same ballpark but having tankers aoes use more standardized/intended damage calculations.
If a more concrete example would help folks doing standardized testing by running maps on live and on the beta server using the same character are reporting 20-30% longer clear times on the beta server. So don't worry, it's not another buff to tankers.
