Not sympathy, really. Also, I think there's more to it than just on the pitch. If Cahill was VC last season, and he doesn't appear to be that vocal on the pitch, then he must be a very respected figure in the dressing room.
I just think, in this particular situation, since Cahill has been captain (all of last season) and is a likely starter, that giving it to someone else is the same as stripping it from him. I just don't like the idea of taking it away from somebody.