Every album is the greatest thing the band has ever done, according to the band, while it's being made and after its release. They're thrilled with the results, and know the fans will be, too. You know the drill.
Then a little time goes by and the excitement wears off, and some fans aren't thrilled with the results, and someone in the band says "Yeah well the label blah blah blah, and we really want to blah blah blah, but I guess blah blah blah".
And let's face it; many fans have strong enough opinions, but many are sheep. Everyone says the one song sucks, so it must suck. Didn't you hear? It's not what the band even wanted to do.