I don't have an answer for you, but I was surprised myself. I found the DNA testing placed me in regions I have no knowledge of via family lore. Also, I was not placed in the areas my family told me we came from.
I'm going to add feedback via the BETA feedback option. I'm very new to ancestry.com and haven't got a family tree up nor much time to do it now, but I am interested in following this particular discussion.
thanks for starting it,