Strictly speaking its a Ballad for Bill but Blues just ‘feels’ better. Being precise is not the requirement of an artist. By definition the artist is a creative and as such can create what they will so long as THEY believe in the art THEY create. Adding words to it isn’t really the domain of the musical artist. That is for others to imagine either absurdly or precisely or by adopting a relevant patois. If you want words why have you got ears?