Honestly that sounds like a decent theory and the only one that sorta makes sense. Looking at the VS devaluation late last year BA now seems to have brought their redemption rates closer to what VS did though VS has slightly different bands and left their sub-650 mile band alone in Y (which is actually my biggest use-short direct flights). At this point you are right BA is mostly dead for redemptions on AA/AS metal, on a very short haul route I book a lot on (that has relatively high cash rates as times) I did see one flight where AA was charging 13k and BA 12k but the cash price was $195 so I'd likely just pay cash unless I valued a refundable ticket.