The real test of a career is during the lows, and not the highs. Ask yourself...if the masses turned their back on your fave for an album or two...could they survive that? What would they sell? Charts? Tour? If they fell down the hitmakers rankings...could they write themselves a get-out-of-flopping free card?
PRISM has been in the top30-20-10 whatever (much higher than ARTPOP) ever since it went up for preorder
ARTPOP was extremely frontloaded
it basically free fell out of the iTunes top100 after like 1 week and hasn't recovered even though she did promo (radio/tv interviews+performances)