AFAIK the A fare is a Y up fare. Its like an AS value fare that automatically upgrades a gold except that anybody buying it can auto upgrade. I dont think they count as 50% EQM bonus when crediting to MP but I could be mistaken because it probably depends on what DL is sending it to AS as an upgrade or as F class. Delta, AA, and many others play a game with EQM miles where as even full Y tickets earn extra eqm miles of either 25% or 50%. AS doesnt play that silly game.
It isn't a "silly" game because the full Y tickets are more expensive than the "Y"-up fares which actually are a lower class than Y (otherwise, they'd be refundable). They are more expensive than the AS F bucket, which is typically what the "up" fare is on another airline. So, AS has no reason to play "the game" but for the other airlines, it makes sense to please the customer with the bonus.