Minor issue, I figured it would be fixed by now but maybe it isn't known. The API reports appear to be missing the [Hero of the Alliance: Ruthless] and [Hero of the Horde: Ruthless] achievements (IDs 6316 and 6317). The total achievement points of people with this achievement do not include it (i.e. 10 points too low) and achievement data queries (fields=achievements) are missing it. The regular armory does actually include these achievements and accounts for them.
Note the 10 point difference:
http://us.battle.net/wow/en/character/mannoroth/Vasku/simple
http://us.battle.net/api/wow/character/mannoroth/Vasku?fields=achievements
