Sure it changes things, but is that what would make a good acoustic response? There is much more to this than bringing it in the room and what one thinks sounds good. What is that 'good' compared to? A concert hall, just a difference from the previous room setup? The local pub's trio?
Yes, that waterfall chart helps, but that one is based on their controlled room conditions, or someones room not yours. Can you do the same graphing, at any location in your room? If so, then yes, you can objectively set them up where they need to be, not where one may think it sounds best as they may not coincide.