I don't play anymore, but from what I've read elsewhere, PA is heavily countered by buying armor items. Shiva's Guard was very popular in this meta, so that makes PA unpickable. Magic damage was also very strong this year, so her innate evasion is useless and she can't fight without BKB.

She also needs battlefury to farm, so she's very slow. By the time she's ready to fight, teams will have already itemized around her, once again making her useless.