Oh god, Nickelback. But anyway, record sales are going to become more and more unreliable in determining a band's worth. Think about how many people are downloading albums instead of going to the CD store (are there even music stores still open? All the ones in NYC are shutting down) or Amazon.com or the iTunes store and actually buying a copy. So there might be, oh, say, nearly a million (random figure) people who are fans of said band, but they just did not buy the album for whatever reason they choose.
That is a demographic that takes away from album sales. So sure, back in the early 2000's, Creed went double platinum or whatever y'all say (I really do not keep track of such stats so I am piggybacking here). But if 'Full Circle' does not reach the same heights, there are likely two possible reasons -- 1) people stopped giving a shit or 2) more people downloaded the album than bought it.
So maybe chart positions really do not mean shit, despite whatever the thread-starter said about Nickelback.