Those are not Butterfly stains, they are not stains at all, it is graping caused by the buds on the tree not being wiped off and small branches forming. They are a lot harder than clean willow and although they will reduce performance they will stop that area from damaging so good in the toe.
I'm not afraid to admit that I'd want them in the back rather than the face but it seems odd that there has not been a forum trend for Butterflys.I have clefts available if we are starting one....