A lot has changed since James Mercer formed Broken Bells four years ago with producer Brian Burton, aka Danger Mouse. Broken Bells' roots can be traced to when Mercer lent his voice to the squiggly oddity "Insane Lullaby", a track that landed on the Burton/Mark Linkous project Dark Night of the Soul. You can also draw a line from Mercer's previous album with the Shins, Wincing the Night Away, which moved away from the spiky guitar pop of their first two star-making records towards moodier, more impressionistic territory. A subtly excellent album that has benefited from the passage of time, Wincing the Night Away nonetheless sounded like a statement of defeat from a songwriter who had experienced major success earlier in that decade.

Broken Bells' self-titled album arrived as the prospects of a new Shins album dimmed, so the new group's existence alone prompted a sigh of relief. You heard the 2010 debut and the accompanying Meyrin Fields EP and thought, well, if this is what Mercer plans to do with his time, it could be worse. Two years later, he shattered this notion with the Shins' fourth record, Port of Morrow, an energetic, colorfully overstuffed collection that showcased his maturity as a real-deal vocalist. The Shins' successful return upped the ante for whatever Mercer tried next and, two years later, we have Broken Bells' second album, After the Disco.

The first Broken Bells album was an eclectic, low-stakes affair that, at its best, came across as two seasoned musicians taking advantage of a major-label budget (the list of additional contributors dwarfed Port of Morrow's considerable collab-a-palooza). The record dipped in and out of different sounds and styles—wheezing indie-pop, drum-machine percolators, Beach Boys-style funhouse psychedelia. The songs lacked the staying power of the Shins' best work but there was enough sonic variety to make for an intermittently engaging listen.

After the Disco is a more cohesive record, and that turns out to be the problem: Mercer and Burton's eccentricities have been sanded down to a single, flattened plane. Broken Bells have been fond of outer space imagery—Christina Hendricks' turn as a vacationing astronaut for the video for Broken Bells' "The Ghost Inside", the similarly astral series of short films accompanying After the Disco's singles—and this set represents the sonic manifestation of their space-is-the-place mindset, with music that is weightless, atmospherically heavy, and inert. The LP's title suggests that Broken Bells' attentions have turned to the dancefloor, and to a point that holds true—there's the perky beat and synth stabs of the title track, Mercer's strange Bee Gees affectation on "Holding on for Life", the elided grandeur of "The Changing Lights". But too often, these songs sound lifeless and drained of energy.

Still, Mercer remains one of North America's stronger melodic songwriters. His sing-songy cadence on the verse section of "After the Disco" proves an instant earworm, and the acoustic dusk of "Lazy Wonderland" stands with the best in Mercer's catalogue, reminiscent of Port of Morrow's lovely, languid "September". But these glimmers of warmth quickly fade in After the Disco's chilly environs; as soon as "After the Disco" hits its bridge, the melody falters and Mercer is forced to hop around in his vocal range, coming across as bad karaoke. Meanwhile, it's possible to pinpoint to the second where "Lazy Wonderland" heads into leaden territory (1:28) with dramatic strings and a suffocating sense of self-importance.

Strings and self-importance are par for the course for Burton, and you have to wonder if he's the album's weak link. A capable producer who made his name a decade ago by hitting the zeitgeist jackpot with his Jay-Z/Beatles mash-up LP The Grey Album, Burton has had success as a consummate collaborator—2003's inventive Ghetto Pop Life with rapper Jemini, the retro-tripping soul of his and Cee-Lo's Gnarls Barkley project, his stoned, giggly collaborations with DOOM, the diffuse melancholia of Beck's underappreciated 2008 album Modern Guilt. But in 2014, it's hard to identify what makes him distinctive apart from his client list. His penchant for foggy psychedelia peaked on the Black Keys' solid 2008 LP Attack & Release, and since then the projects he's been involved with have been comparatively stiff, like his melodramatic LP with Italian composer Daniele Luppi, 2011's Rome. When the strings come in on After the Disco's "The Remains of Rock & Roll" (sometimes the jokes write themselves), it inspires fantasies of Danger Mouse projects that feature, well, less Danger Mouse.

For his part, James Mercer has proven amenable to collaboration. On Port of Morrow, the Shins' new line-up functioned essentially as anonymous sideman as Mercer employed a DJ Khaled-sized cast of collaborators. That record's try-anything approach confirmed that, whether it be Steve Miller Band rip-offs or spiky new-wave callbacks, his aesthetic can fit into any style. This sense of game-for-whatever adventurousness has to be why he continues to work with Burton as Broken Bells, but given the Shins' continued success and growing range, and what Mercer and Burton managed here, it's hard to think of why this project needs to exist.