After the Decemberists played the driving, lyrically ornate "The Infanta" at the Academy of Music on Tuesday night, singer Colin Meloy made a confession. The song, he told the audience, "serves no practical purpose whatsoever." It was a strange moment, not because he was wrong, but because the issue of practicality is not one that seems to weigh heavily on the band's collective conscience.

Over the last 15 years, the quintet from Portland, Ore., augmented on stage by singers Kelly Hogan and Nora O'Connor, has built a devoted, ever-growing fan base with elaborate, hyperliterary folk tunes - a cross between a medieval history seminar and an advanced vocabulary quiz.

"And above all this folderol / on a bed made of chaparral / she is laid, a coronal placed on her brow," isn't normally stuff that burns up the pop charts. But 2011's The King Is Dead gave the band its first No. 1 album. Having scaled those heights, Meloy and Co. took a break: Meloy worked on a trilogy of children's books, The Wildwood Chronicles, with his wife, Carson Ellis, and spent time with his two children; the rest of the band played in their side project, Black Prairie.

Rather than stockpiling 10-dollar words during the hiatus, Meloy took a few tentative steps toward transparency. "The Singer Addresses His Audience," the first track on the new What a Terrible World, What a Beautiful World, is hardly a straightforward burden-of-fame lament:

"We're aware that you cut your hair / in a style that our drummer wore / in the video" sounds like the front man of a slightly more fashion plate-y ensemble. But "12/17/12" - the date of President Obama's speech after the Newtown school shooting - drops the band's signature shtick for something approaching straightforward emotion - which is not to say, in Meloy's world, that anything is ever truly straightforward.

Drawing on nearly every album in the band's career - only 2003's Her Majesty the Decemberists got the shaft - the 100-minute show ranged between the wry pomp of the three-part "The Crane Wife" to the quasi-rock thunder of "The Rake's Song," which pumped some much-needed blood into the proceedings. The blood kept flowing in the show's second half, with the relatively upbeat, or at least up-tempo, "16 Military Wives" and "O Valencia!" serving as a reminder that Meloy can write exceptionally fine tunes that aren't as weighed down by mock-complexity as his words. On stage more than on record, his tongue never quite seems to come out of his cheek, and his attempts at winsomeness - introducing "Calamity Song" with a ditty written to persuade his 4-year-old son to eat his oatmeal, or dropping in a brief interpolation of the Doobie Brothers' "Black Water" - merely came off as cutesy. The Decemberists don't seem capable of, or interested in, playing it straight, but they're best when they at least half-try.