Punch Brothers play a fascinating game—over the course of their now-four albums, they’ve done everything they can to prove they don’t do “exactly what it says on the tin.” Despite their instrumental makeup and their individual histories as exemplary players in the idiom, they’re not really a bluegrass band. Following their neo-classical debut with albums successively helmed by modern alternative masters Jon Brion and Jacquire King helped solidify that concept, so teaming up with T Bone Burnett for The Phosphorescent Blues might seem like they’re finally circling back around to their roots. Instead, as the lush, Pet Sounds-inflected opener “Familiarity” suggests, Punch Brothers may have made their most “pop” record yet. Despite two brief detours to Western classical territory, overall the least contemporary aspect of the record is the instrumentation—which, in this case, is even bolstered by the capable but unnecessary drumming of Jay Bellerose. Burnett’s typical concision works best on “Magnet” and “Between 1st and A,” but he’s a savvy enough producer to stay out of the way of a sprawling epic like “Familiarity,” allowing for an end product belonging to the tradition of majestic pop that stretches from Fleetwood Mac’s Rumours to Arcade Fire’s The Suburbs.