I have a similar hen who has been moulting since I got her. Originally I thought she was a dark brahma mix because that is exactly what she looked like minus the feathered legs. My hen is a large bird with a pea comb. I have sinced decided she is a wyandotte probable mix.If she ever fills in her tail she will probably be a pretty bird.
If she's a mixed breed, she's a mixed breed. Not much more to say about that. Are you wanting to know what the barred rock was crossed with? She's a pretty bird that lays good eggs. Nuff said.
She doesn't have any barring or resemblance to it, so I'd say there's no Barred in her at all, and her body is pretty thin looking. . . I'd say she might have Easter Egger or something else in her, but not Brahma and likely not Rock either.