I'd assume poetry sales (or lack thereof...) do have something to do with it, though maybe not in the sense that publishers pressure the SA. More so in what gets attention, and therefore gets translated, and therefore gets international attention. And there also may be fewer people pursuing poetry as a career at the level they're looking for due to economic pressures. There may just be fewer poets on their radar who they'd seriously consider when compared to the past. (This is more of a gut feeling, though, not backed up by stats or anything.)