Quote:
Original posted by ajohn at 8/10/2015 15:18 
It looks like a juvenile Dark-sided to me.
- The underparts appear to be mottled with dark, rather than showing defined streaks
- The bill looks relatively short, and mostly dark
- The eye-ring broad ...
I agree with your excellent assessment that this is a first-winter Dark-sided flycatcher. I just found a paper entitled "Brown, Siberian and Grey-streaked Flycatchers: identification and ageing" by Paul J. Leader (British Birds 103. November 2010), which gives detailed discussion on the differences between Asian Brown, Dark-sided and Grey-streaked, covering both adults and juveniles. The section on 'Wing shape and primary projection' and Fig. 2 are particularly helpful in further supporting that this is Dark-sided.
