lpaul

This looks like a good first-winter Red-breasted Flyc to me.  In addition to the points listed by Geoff the more uniform underparts lacking the well defined pale throat (similar to female Bluetail) also separate from Red-throated.  Plus the larger more buff tips to the greater coverts are typical of first winter Red-breasted.

lpaul

I have however seen Red-throated forage in the mid canopy on migration.

It does seem odd that the eastern edge of the breeding grounds is so far west, however there are other comparable examples such as Amur Falcon which breeds no further west than Qinghai, yet winters in Africa.  I think a suggestion from John Allcock makes most sense; that it regularly winters further east than the literature suggests.  This seems more likely than the distinctive males being overlooked on the breeding grounds or in the extensive Russian bird collections.

The real question now is how regular is it?