Prepare to be both impressed and completely appalled.
In 'Live By Night', Miller plays "not the sort of girl you'd bring home to meet your mother" during Prohibition era Boston and has an Irish accent that moves all the way from Dublin to Cork (apparently via Russia?), adding her name to the canon of actors who have made an absolute hames of the way we speak.
The strange thing is, when challenged to do an Irish accent on live TV by Today's Matt Lauer, she pretty much nails it. So the real question is, are all terrible accents Ben Affleck's fault?