WoD Beta - How to get Into Warlords of Draenor Beta

I still don't know whether for some bizarre reason I had Alpha access, but now my Battle.net desktop app does actually say Beta, rather than Alpha.

The guys over at The Instance and Convert To Raid were debating last week as to what contributes being a veteran, which grants you an invite to Warlords of Destruction (sic) Beta.

Well, I'll tell you my circumstances.

• I began playing in Vanilla (sorry Koltrane - I mean Classic!!) before the Gates of Ahn'Qiraj patch. 
• I have never let that account's subscription lapse (except maybe a day here and there). 
• I have had a second account since the start of TBC and that has also rarely lapsed and was merged along with my main account into my battle.net account as soon as it was possible to do so. 
• I have a third account which was active for a couple of years but is now dormant. 
• I bought the 1 year subscription to get me into MOP Beta and did actually log into it and use the Beta Account. 
• I have Diablo 3 and Starcraft 2 + Expansion on my Battle.net account. 
• I have a Hearthstone account. 
• Very importantly I opted in for the beta.

 So, I think the criteria are:

1. You opted in for Beta
2. You have an active account in good standing
3. You have played since Vanilla 

 There you go, that's my theory. Prove me wrong!