hybrid Clay-colored x Chipping Sparrow? (1 Viewer)

The images attached show a first-winter sparrow with facial features of Clay-colored (pale lores & distinct moustachial stripe et cetera) but the rump and breast colour are atypical. Some Clay-colored Sparrows do exhibit gray rumps but there is usually an overlaying tone of buff and the overall area does not stand out as sharply. The breast is highly unusual for a first-winter Clay-colored (see streaking on sides of upper breast indicating age). What are your opinions on this being a hybrid Clay-colored x Chipping Sparrow? The only photograph I could find of such a bird at this age showed some reddish tones on the crown and a slight grey line across the lores.