Is it a shock? Yes, but I can't say I'm too crestfallen. While they will always be a legacy band and Images & Words will always be a top-10 album, the truth is that I just haven't listened to them much and the last 3 or 4 cd's only had a few songs on each that got repeated listens from me. I'm always much more excited to hear the new Nevermore, Opeth, or Lamb of God material, or any of the other great bands I've discovered over the past few years than the same mid-tempo, ballad-filled stuff DT has been putting out. They can still shred with the best of them, but to me they lost their edge a long time ago.
I wonder how much of his involvement with Avenged Sevenfold led to this - they are one of the worst bands to ever wear eyeliner, but they are popular with the young Hot Topic crowd of lite-metal for girls and sensitive guys and I'm sure they sell a ton of records and sell out big arenas every night. While DT is always going to have that built-in fanbase that will sustain them, maybe MP sees a big pile of money sitting in front of him that he knows would take another 5 years or more to get with DT, and he wanted to grab as much as he could while it was still on the table. He has also done a lot of side projects, so maybe they both go their own way for a few years and then they'll kiss and make up for a 30th Anniversary reunion cd and tour.
