That's not entirely correct. I would argue that the high elves are not fanatically Alliance. They have closer ties with the Kirin Tor than they do the Alliance. If high elves were fanatically Alliance then they would have had an observable presence in this faction war... which they have not.
High elves in most cases are featured as representatives of the Kirin Tor aiding the Alliance, or in some cases even aiding the Horde.