The head and bill shape are somewhat exaggerated in this photo,the head appears more flattened and the bill longer at this angle. The plumage pattern is all very nicely there though. Thayer's should show more-heavily marked, generally dark-centered tertials, and I don't think will match the primary pattern shown by this bird. I came out on the losing side of a battle with some harsh sunlight during most of these photos. The photos of Thayer's that I've run across that come close to matching this bird in plumage are much more obviously worn and Sun-bleached.