Running into different people and you’re having different experiences.
Shocker.
Who are you and why should I care about your opinion?
There is something we are missing but I doubt it is expac only as it even says lifetime. Im doubting you remember exact numbers of bgs youve ran same as I was surprised at just how many AVs I have done.
This isn’t the issue go in game, open achievement tab look at the bottom hit statistics go to pvp. Those numbers are not matching to what is on the website. At least for me
Sorry this is BS… This is the same on both sides. I have played on both sides and in BG focused guilds and BOTH alliance and horde are one in the same. Only in a guild setting will be learn and understand. Why? Because they want to have their friends backs in PvP. Those not in your guild will do what they want (99.9% of the time) Why? Because they don’t know you or care what you want or think or feel. They are there to see their name up to the top on Kills or Damage or healing, whatever the spec maybe.
Horde and Alliance are one and the same. My final point is that many, many and i do mean many Horde in BG are alliance and many alliance are horde. they play both factions. So there is no difference. IMHO
It is both rated and randoms combined, yes.
The in-game stats page splits them I think.
Matches mine to the T:
https://imgur.com/a/UUMO10e
and doesn’t include rated
That’s really strange. Some of my characters are right but my DK for example is missing almost all of the stats in some BGs, like EOTS and epics. Seems to count rated on some as well… and others not. 
But either way, armory is not expansion only.