Today I had all four AA domestic legs of an ex-DUB booking change, all by less than an hour. Most significantly one leg had changed from F to Y class and there are no longer domestic F cabins on that route. I called up BA (who the trip was ticketed with and ticketed by) and they agreed to a re-route, so instead of A to B to C I am now doing A to D to C.

I guess the downgrade was the part that made the difference, and although the time changes weren't ideal I'd have lived with them. I certainly wouldn't have expected to get the re-routing on the basis of the time changes alone.