It means that Mikael is steering the band more and more towards being a 70's prog rock cover band. Whether you look at the early Opeth (based mainly on Iron Maiden'ish twin guitar melodies) or the middle Opeth (MAYH up to BWP) their sound was defined by the atmosphere they managed to create. And a big part of the atmosphere came from their use of acoustics along with heavy guitars and the way in which they used to mix these together to create emotionally moving music (and I'm not talking about the standard heavy - mellow - heavy progressions, I'm talking about the actual overall sound they created).
All of the albums they have released since BWP lack this utterly. Damnation was obviously a one-off project and I know what Mikael tried to do, but come on. It is utterly unremarkable 70's prog worship and if you are interested in that kind of music you are better off listening to the artists that influenced him to make that album than you are listening to Damnation itself. Deliverance was a barren affair with not a single fully realized song on it but more a bunch of half-assed ideas thrown together. This was partially due to the incredible time pressure under which they had to create these albums (most of both albums was written in the studio while they were recording two albums for the time and money they would normally have for one). That doesn't change the fact that both albums are mediocre at best and lack all of the elements that made older Opeth albums interesting.
They redeemed themselves somewhat with Ghost Reveries where they atleast took some time to actually write and rehearse before entering the studio (and obviously not recording two albums at the same time helps). The album has its moments. But the folk influences that were an essential part of Opeth's sound have been entirely replaced with mellotron-laden prog noodling and Beach Boys style interludes, conjuring up the same prog rock vibe I mentioned earlier. Listen to the guitar sound on MAYH and compare it to GR. The vibe they are going for is completely different these days. And in doing so they completely drained the emotion and subtlety from their music and replaced it with the more overbearing pompous prog rock sound.
Mike is getting old, he has a family and is listening to "old man's rock" nowadays (as he put it). And it shows in the way he approaches writing music nowadays. Honestly I don't have high hopes of anything truly amazing coming from this band in the future.
Though I suppose my obsession with Tolkien at the time of discovery may have been a factor, but I still hold the album in high regard.
