Nope, in the left example the hair should be blurred even in the edges. But the blur should be such that the details in the background are preserved (it seems sightly off). The math behind this afaik is a variant convolution with depth dependent kernel + occlusion. So in the right the hair is sharp because the blurred background is occluded by the sharp hair, but in the left the frontier isn't sharp because the sharp background isn't occluding the blurry foreground.