My hen is a red sex link, probably at least 3 years old (I've had her 2 years, and I was told she was "older" then). The sagginess almost looks like what I'd imagine a beard might look under the feathers (unless a beard *is* just feathers) except Quiche isn't bearded, and it's mostly on her right.
Some pics:
And a pic of my other red sex link, the same age, for comparison (different angle, though) :
Some pics:
And a pic of my other red sex link, the same age, for comparison (different angle, though) :