Like a horror B-movie, “We Were Dead Before the Ship Even Sank” is enjoyable in spite of itself. Although long-time fans of Modest Mouse may be put off by the band’s mainstream success and “Float On” fans may find the new album too abrasive, “We Were Dead” proves worthwhile, if one can persevere. Listening to the album is like receiving an Etch-a-Sketch for Christmas after asking for a paint set: Initially baffling, if not disappointing, but a good product in its own right.

After 10 years of obscurity and three full-length albums, Modest Mouse hit it big in 2004 with the single “Float On,” from their fourth album, “Good News for People Who Love Bad News.” In a matter of months, they went from obscurity to Fenway, having their songs played at Boston Red Sox games. On this latest effort, the band has brought in former Smiths guitarist Johnny Marr, and The Shins’ James Mercer sings backup on several tracks. “We Were Dead” proved to be a big middle finger to those who predicted that Modest Mouse would slip into the indie one-hit wonder purgatory occupied by artists like Edwyn Collins (to those wondering who that is — exactly), when it debuted at number one on the Billboard charts.

After initially stumbling into the pop wing of the indie mansion with the minor-key, optimistic hit “Float On,” Modest Mouse has settled in, perhaps for the long haul, with “We Were Dead.” Although it has gone the route of the poppy, Isaac Brock’s singing continues to be abrasive and pessimistic, addressing darker subjects like his inability to leave his past behind.

The characteristics that render album’s success surprising are most evident with the choice of “March Into the Sea,” the weakest song on “We Were Dead,” as the lead track. The album’s first three-and-a-half minutes of tuneless wandering and aimless instrumentation prepare the listener to be disappointed. The second track, “Dashboard,” the album’s first single, is a rehashed “Float On” — but if “Float On” is a steak, “Dashboard” is a piece of steak overcooked into a charred, flavorless, amorphous mass.

Despite its initial missteps, the album rides on the strength of its variation, as heard on tracks like “Little Motel” and “We’ve Got Everything.” The fact that Modest Mouse brought two artists as different as Marr (guitar rock) and Mercer (lo-fi) onto the same album reflects this variation: Mercer complements Brock’s vocals on the track “Missed the Boat,” adding a depth of sound to what would otherwise be just a flat, mid-tempo, half-assed effort. Marr comes out in full force on the subsequent track “We’ve Got Everything,” an un-ambitious, up-tempo with a catchy hook. The ultimate union of Brock, Mercer and Marr is “Florida,” an alternately jangly and pulsing series of variations, with Marr’s ready-to-burst guitar playing; Mercer’s ethereal, one-man-choir backup vocals; and Brock’s characteristic caterwauling.

“Florida” demonstrates that all the right components are available; Modest Mouse’s struggle with “We Were Dead” was not a failure of ability, but rather a lack of unity. Beyond fitting vaguely into a more poppy sound, the album at times feels schizophrenic, and is therefore tiring. Tracks like “Steam Engenius,” while groove-worthy and great in isolation, get lost in the shuffle and Modest Mouse’s failure to create a cohesive album.