For at least the last six or eight years, no band makes me more nervous than Clutch. Ever since the release of “Robot Hive: Exodus,” the band has left my fanhood on uncertain footing, slowly but surely making adjustments to their sound. As critical praise came easily to “From Beale Street to Oblivion,” many who thirsted for the “Pure Rock Fury” era felt left in the lurch. What were we to make of this new Clutch, with the mellower, more calculated sound? The crowds at the live shows began to shift demographic, skewing in new directions.