I think this is what you are trying to convey:
Upper left photo, front post centered in front sight hood, centered in aperture. Ideal.
Upper right, post not centered in front hood, this would be the correct sight picture.
Bottom, post not centered in front hood, circles lined up, but not front post is not centered, so shots will be low.
I expect this problem could be more or less apparent depending on how good your eyes are.