LOL well done picking out one thing mentioned and automatically assuming that's the only thing they did to improve thermals and power despite them saying they did a lot of work to cut power.
Personally I think they did do quite a lot, perhaps similar to what Nvidia have achieved. My concern would be how much is the GPU more efficient and how much is the HBM memory helping? This will become important next year with the new GPUs because Nvidia will get the same boost from HBM and the gap could increase again. These will be on 16nm new process so lot of things could change.