What makes a song? Is it a series of notes, or is it everything around that core—the production choices, instrumental decisions and vocal inflections that bring a melody to life? Such is the question posed by The Worm’s Heart, the Shins’ sixth studio album. A year-late twin to 2017’s Heartworms, it arrives from a parallel universe where that album has been “flipped”: Slow songs become fast, fast become slow, pop turns to rock and rock turns to disco.

Faced with such an overhaul, it’s tempting to wonder if some simmering discontentment with Heartworms has been keeping James Mercer up at night. But that would be unfair: the Shins’ leader has always been a more experimental musician than he is given credit for, and Heartworms was a strong release, with a compelling production style that jumped between modern electronics, country warmth and good old-fashioned indie pop. For fans of that record—and it is hard to see non-devotees casually investigating The Worm’s Heart—the new album may initially prove hard to swallow.

For a start, it’s all over the place. Expecting stylistic consistency from a release like this may be a fool’s errand. But The Worm’s Heart takes Mercer’s eclectic spirit to groggy new heights, jumping in the first three numbers from the kind of slackened garage rock the Velvet Underground spat up on “Foggy Notion” (on “The Fear (Flipped)”) to a song that resembles LCD Soundsystem lost in the Christmas fog (“So Now What (Flipped)”) to a disco pop belter (“Heartworms (Flipped)”). Later, The Worm’s Heart offers us a piano-led torch song and a rather excruciating dash of rocksteady, neither a sound that anyone was especially clamoring for from the Shins.

The rocksteady number, “Half a Million (Flipped),” is the album’s nadir, strangling the song’s delicate melody with jaunty guitar chords out of “Ob-La-Di, Ob-La-Da.” Joining it in shame is “Mildenhall (Flipped)‚” which acid-washes the original’s laid-back country charm in the kind of beery rock drawl that bar bands revert to when they start running out of songs. “Name For You (Flipped)” is pretty horrible, too, drenching the goofy sweetness of the original in gloomy synths and distorted guitar.

Against these lows are two songs that rank among the very best in the Shins’ catalogue. “Cherry Hearts (Flipped),” originally a confused synth number, is transformed into a chest-beating rock anthem thanks to a fabulously Who-esque guitar riff. “Heartworms (Flipped)” goes the other way, mutating from a soporific, guitar-led daydream into an electrifying disco number that rouses like a long-lost ’80s hit, with a throbbing synth line and drums that stomp like Prince. Elsewhere, the impact of these transformations is less extreme. “Rubber Ballz (Flipped)” is an acoustic take on the Beatles-y Heartworms number that matches the original’s understated appeal, while both “The Fear (Flipped)” and “So Now What (Flipped)” end up feeling neither better nor worse than their 2017 editions, just different.

In the end, The Worm’s Heart proves the fairly obvious point that both song and surroundings are important, and reminds us that Mercer is an occasional master of both. It’s a pleasant oddity in the Shins’ catalogue—neither a dazzling reinvention of the original release (see: Massive Attack V Mad Professor’s towering No Protection) nor a hastily-assembled insult to the band’s creative work (like TRON: Legacy Reconfigured). If nothing else, it lets you cherry-pick the radical brilliance of “Cherry Hearts (Flipped)” and “Heartworms (Flipped)” for a playlist and forget the rest.