By Jonathan Blumhofer

Interpretively, this installment in the BSO’s cycle of Dmitri Shostakovich’s 15 symphonies is occasionally (and a bit surprisingly) spotty.

Rare, indeed, is a flawless cycle of Dmitri Shostakovich’s 15 symphonies. As we’re reminded with the latest volume in Andris Nelsons’s ongoing survey of the set with the Boston Symphony Orchestra (BSO).

To be sure, what’s come before has set a very high bar and none of the present performances are lacking, technically. But, interpretively, this installment — which combines the First, Fourteenth, and Fifteenth Symphonies with Rudolf Barshai’s arrangement of the String Quartet no. 8 (as the Chamber Symphony in C minor) — is occasionally (and a bit surprisingly) spotty.

The most compelling performance here belongs to the Symphony no. 1. Completed when Shostakovich was just 19, this is music of breathtaking personality, technique, and heart.

While not as subjective a reading as Leonard Bernstein’s overwhelming 1988 recording of the piece with the Chicago Symphony, Nelsons’s account is commendably focused, intense, and searching.

For instance, he draws plenty of snark and irony from the BSO in the cheeky first movement. But he also gives the orchestral soloists room to shape their lines and tap into the music’s underlying pathos. The second is spry and lively, the contrasts between its two main themes strongly delineated; Vytas Baksys’s execution of the keyboard writing leaves nothing to be desired. In the slow third movement, there’s a wonderful sense of space — not to mention melting solos from principal oboe John Ferrillo and principal cello Blaise Déjardin. The finale is clean, well-shaped, and exciting.

Juxtaposing the First Symphony with the Fifteenth, Shostakovich’s last, makes for a smart program. Premiered in 1972, the latter score shows a mastery of the arts of sarcasm and ambiguity that’s only hinted at in the earlier work. The music’s quotations — of the William Tell Overture, Wagner, and Shostakovich’s own oeuvre — give the Symphony a weird, unsettled edge (as well as provide it an enigmatic reputation). But its overarching arguments are cogent and, in the right hands, the Fifteenth stands as one of the great symphonies in the canon.

Here, Nelsons is generally one of those interpreters.

The irreverent first movement and sardonic third are appropriately light and agile. He draws fervent solos from the BSO in the big second movement. And the opening of the finale is profoundly lyrical.

True, tempos in those second and fourth movements are expansive to a sometimes disorienting degree. Yet the performance manages to hold together and it’s fascinating to hear the finale slowly lift off and dance.

What we’ve got here, then, is a singular interpretation of the Fifteenth. It’s probably not the only one you’ll want to have, but in a field already crowded with contributions from the likes of Barshai, Järvi, Solti, Haitink, Wigglesworth, and Petrenko (among others), Nelsons and the BSO have managed to chisel out their own little shelf. That’s an impressive accomplishment.

Alas, they don’t manage quite the same with the 1969 Fourteenth Symphony, a setting of 11 poems that meditate on death and decay. Here, Nelsons & Co. are joined by soprano Kristine Opolais and bass Alexander Tsymbalyuk.

Granted, this is a tough score to sell and, while the orchestral contribution is bleak and well-played, the larger performance lacks the intensity and terror of Barshai’s debut recording of the symphony.

The singing, too, is uneven.

Opolais, with her light tone and big vibrato, sounds like a fish out of water. While her quieter moments — like the end of Guillaume Apollinaire’s “Loreley” or the beginning of the same’s “The Suicide” — are fine, the big ones are too often strident, wobbly, and blurry of pitch and/or diction.

Tsymbalyuk, on the other hand, is a model of precision, restraint, and power. His tone is velvet, intonation true, diction immaculate. Apollinaire’s “Reply of the Zaporozhye Cossacks” and Wilhelm Küchelbecker’s “O Delvig, Delvig” are exquisitely sung.

Rounding things out is Nelsons’s Delphic take on the Chamber Symphony. On the one hand, the BSO strings sound rich and lovely. There’s plenty of weight to this performance (especially the outer movements) and nobody’s going to argue that the reading’s mien isn’t brooding or melancholy.

Yet Nelsons’s penchant for spacious tempos more than once undercuts the music’s sense of urgency, especially in the first and fourth movements. The second is leaden. Often enough, the sheer size of the BSO’s string complement robs the score of intimacy and flexibility. Barshai’s own recording, with the Chamber Orchestra of Europe, wants nothing for either of those; his tempos, too, are generally — though not always — fleeter.

Ultimately, then, Nelsons’s interpretation is more sluggish and resigned than not — which is certainly an approach to the piece; just maybe not the best one.

As has been standard for these Deutsche Grammophon releases, though, the album’s engineering is resonant and warm. There are a handful of glimmers of audience noise, yet they never distract from the proceedings.

Jonathan Blumhofer is a composer and violist who has been active in the greater Boston area since 2004. His music has received numerous awards and been performed by various ensembles, including the American Composers Orchestra, Kiev Philharmonic, Camerata Chicago, Xanthos Ensemble, and Juventas New Music Group. Since receiving his doctorate from Boston University in 2010, Jon has taught at Clark University, Worcester Polytechnic Institute, and online for the University of Phoenix, in addition to writing music criticism for the Worcester Telegram & Gazette.