Here's the thing. I can sit here and argue all day long why I think Blackwater Park is Opeth's worst album and why Watershed is so much better than BWP. However, it's an opinion. ...and for the most part, there's a lot of freedom over opinions on a forum.
I really like Watershed as an album. It's in my top four realeases from Opeth. But, I can understand why there'd be a lot of negativity towards it. Or, why other's would like other discs moreso than Watershed. But, it's a moot point to sit there and get bent out of shape that some people may not care for the new record in respects to the band's other releases.
I've made this comment before. Opeth has one huge problem. ...and that's diversity in their song writing. You take a band that has death metal influence, black metal influence, classic rock influence, progressive rock influence, glam rock (and glam ballad rock) influence and many other styles. You can't please everyone, it's just not possible. Opeth has not gone the mainstream route and tried to sell out. Mike has taken the band in his direction. Similar to Dream Theater, when Opeth releases a new album you're going to hear the usual rants, "It's too heavy, it's too soft, it's too proggy, there's not enough guitar diversity, it's too focused around guitars, it's too focused around keyboards, etc." and the list can go on and on. Opeth's biggest problem with fan base is that they draw fans from an eclectic background of music genres. They're not like a Slayer where every record sounds like their last. They're just plain Opeth. The band is going to do what they want to do musically and do things the way they want and have fun doing it. Opeth cannot, at this point in their career, please everyone one of their fans when the 'proverbial' new record releases. Unfortunately, as a fan, you'll have to come to terms with that!
With that said, don't interpret that in any wierd way. Please don't take that as a shot, I'm just stating the obvious about their fan base coming from different musical backgrounds.