Imagine for a moment that on the lonely Friday night depicted in the Strokes’ 2003 single “12:51,” frontman Julian Casablancas decided to hit up a dance club rather than crash the drunken house party mentioned in the lyrics. The result would sound something like “11th Dimension,” the first single from Casablancas’ premiere solo album “Phrazes For the Young.” Featuring a bubbling electronic beat layered with disco sheen and synths torn from the Human League’s new wave cornerstone “Don’t You Want Me,” “11th Dimension” does not resemble anything ever produced by the Strokes, which reflects the larger point of Casablancas’ solo album. With his band, Casablancas produced tight, punk-tinged garage pop; on his own, Casablancas clearly has greater ambitions and a more varied, chameleonic style, a fact that comes through on “Phrazes,” albeit with mixed results.

Unfortunately, a nearly four-year studio hiatus seems to have somewhat dulled Casablancas’ previously superb songwriting abilities. The album’s opener, “Out of the Blue,” rides a driving guitar riff resembling something from a punk rock Johnny Cash as Casablancas delivers one of the album’s best lyrics: “I know I’m going to hell in a leather jacket / at least I’ll be in another world while you’re pissing on my casket.” While Casablancas’ freewheeling tone adds a sense of fun not heard in his voice for several years, it doesn’t distract from the fact that the song never really moves anywhere. The same hook repeats for five minutes, without any substantial increase in excitement or drama.

The same principle holds true for “River of Breaklights,” in which Casablancas mindlessly chants, “Getting the hang of it, timing is everything,” over a generic, messy background of drums and guitar. Casablancas holds to the false impression on “Phrazes” that a fast tempo alone always conveys a sense of urgency or energy. He fell victim to similar problems on his later Strokes songwriting—think “Juicebox”—and has failed to correct such issues. “Brakelights” does not offer any compelling musical ideas with the exception of a breakdown with computer-generated blips reminiscent of the Super Mario Bros. soundtrack.

The uninspired “Glass” recalls “On the Other Side” from the Strokes’ 2006 release “First Impressions of Earth” with a syncopated beat and slowly progressing guitar chords. As Casablancas wails muddled lyrics such as, “I don’t believe it / I won’t believe it,” his usually appealing nasal, alien-sounding baritone starts to strain, proving that he truly sounds better as a singer at faster tempos.

It is in the moments that Casablancas breaks free of midtempo rock and experiments with his sound that “Phrazes” truly shines. “11th Dimension” is undoubtedly the finest track on the album: an ’80s new-wave homage recalling the post-punk roots of New Order, “Dimension” showcases Casablancas truly having fun, as he gleefully exclaims “I got music coming out of my hands and feet!” Similarly experimental, the bluesy “4 Chords Of The Apocalypse” opens as a keyboard-fueled shuffle before devolving into a grungy rave-up in the chorus with Casablancas shredding his vocal chords over churning twin-guitar solos. The closer “Tourist” resembles the Led Zeppelin classic “Kashmir,” featuring its galloping drumbeat and Middle Eastern-sounding, snake charming guitar lines that rhythmically shift to accomadate the addition of space age synths. Casablancas’ experimental instincts add a much-needed dose of variety to the album, seeing as many of his other tracks end up sounding like weak Strokes B-sides.

Casablancas’ lyrics work best when he embraces his appointed role as a lovable indie rock miscreant, guilty of overindulgence and carelessness. The excellent “Left & Right in the Dark” incorporates hand claps and a shimmering synth melody into his vocals about not knowing his way in the world: “I’m on my way, oh somewhere / Feels like I’m going left and right in the dark.” He brings a familiar tone of an unapologetic malcontent to “Ludlow Street,” which features a bizarre sitar introduction before transitioning into a boozy, demented waltz. Over a skipping drum machine and pleasant guitar strumming, Casablancas’ wistfully praises common street musicians while condemning the “yuppie expansion.” “Everything seems to go wrong once I stop drinking,” he bashfully declares at the song’s opening. He’s one of the decade’s finest punk rock ne’er-do-wells, and his music reaches its maximum potential when he embraces this role rather than rejecting it.

Casablancas’ solo debut is a confusing experience. Despite running 40 minutes, “Phrazes” is a mere eight tracks. Consequently, the album feels too short while most of the tracks feel too long. His output is erratic: “11th Dimension” and “Left and Right in the Dark” stand among his finest work, while the rest of “Phrazes” suffers from a lack of creative inspiration. Casablancas’ solo effort proves that the Strokes truly were greater than the sum of their parts. For now, as the Strokes record their next album, “Phrazes” is a decent placefiller, but certainly not an enduring, compelling masterpiece in its own right.