I'm not one to put Brann Dailor in Neil's class, but even you gotta admit that the old man has slowed down quite considerably in the last few years. So much so that I would call Peart a mildly imaginative standard rock drummer now rather than the progressive god he once was. And I am saying this as a person who when I was a teenager in the 80's had posters of Peart all over my walls, so I have the right to "constructively critisize."
All of that is undeniably true, but the only way in which Dailor is imaginative, in my opinion, is seeing how many notes and fills he can artlessly cram into a single bar of music without any regard for pesky things like "feel" or "groove."
I love the other 3/4 of Mastodon but he's just in the wrong band.