Coheed has not released a bad album yet. You could say they've grown, matured, changed or any other number of verbs that describe what bands do from album to album, but you can't say they haven't produced Coheed albums. They've been one of the few bands that consistently produce high quality records, regardless of what the "core" fans might think. This is the exact same shit that happens with Say Anything records. They release good albums, but they'll never be like IARB. It's just the way it goes.
As for The Afterman: Ascension, it is a great album, just like all their other albums. If you didn't like them, that's your deal.