I'm now convinced that it is an adult Cooper's Hawk.
I contacted an expert in the field and here's what he had to say:
Your bird looks like an adult Cooper's Hawk to me. Without something of known size in the picture it is hard to assess the bird's size, but it looks big. It looks like it is just completing its annual molt, as expected at this time of year, with the central tail feathers not yet finished growing. (in the Cooper's Hawks adults always have yellow eyes)
Philip Unitt
Collection Manager
Department of Birds and Mammals
San Diego Natural History Museum
I'd like to thank Philip for his help....