The hyperboles in here.
Yes Gaga has declined a bit, but it's not as extreme as you guys make it sound. Obviously there was no way that she was going top or come close to BTW's opening numbers. BTW is a clear anomaly.
BTW put aside, ARTPOP has debuted higher than The Fame and The Fame Monster, the latter which had a huge single around it.
Gaga is still able to find a hit (Applause). Her album sales are now pretty much on par with the rest of the pop girls, which is just fine.
What comes up must come down a bit. S'nothing to freak out about.
So no, it's not her lowest.