Portland’s The Decemberists brought their brand of whimsical folk rock to the Riviera Theatre on Thursday night. While their two-hour set of towering climaxes and bittersweet reflections was played in high spirits and to near perfection, the show seemed to suffer an odd case of split personality syndrome.

At times, The Decemberists seemed a bit sleepy during the second half of their performance, which is understandable for a band that has been touring constantly since the release of the last effort, Hazards Of Love, last March.

Thursday’s show at the Riviera was the third show the band has played in Chicago in the last three months including a Lollapalooza performance and a festival aftershow. Front man Colin Meloy even admitted his joke about the Chicago’s “Chi-Town” moniker pronunciation was rehashed from previous Chicago stops. Still, the band never wavered when they delivered two sets, one with new material and one with old. But it was this show design – two separate sets – that hindered the show’s flow and rhythm.

The Decemberist’s first set was their new album Hazards Of Love in its entirety. The album itself is a sleek, poppy, and at times, a cheesy rock opera about lost love, which is told in Meloy’s rich lyrical tapestry (Tiga?). Yet it’s the cheesiness factor that makes the album so appealing. While other bands are trying to innovate to find a new sound, the Decemberists chose to evolve by evoking the spirit and fire of The Who’s big guitars and Fleetwood Mac’s mystic story-telling.

As a live piece, the album comes off as energetic and theatric. Songs weave in and out of each other and thematic elements often reoccur. The band even brought Hazards’ guest singers Becky Stark (of Lavender Diamond) and Shara Worden (of My Brightest Diamond) on the road with them, as they’re both vital reasons why the album works so well.

Hazards’ centerpiece, “The Wanting Comes In Waves/Repaid,” has quickly become a crowd favorite. The crowd erupted and waved fists in the air when an uplifting section transformed into a Zeppelin-esque, classic rock riff stomper complete with sultry lead vocals provided by Shara Worden. Later, the anthemic “The Rake’s Song” garnered the biggest audience response of the night with its simple and effective refrain, “Alright, Alright, Alright!”

Unfortunately, after the band raced through the nearly hour-long Hazards Of Love, they took a nearly 15 minute break, which really hurt the show’s flow. Once the band came back, they played another 45 minutes of older material.

But this is not to say their older material doesn’t hold up live as well as their newer songs. The 2006 track from The Crane Wife, “O Valencia,” was an audience sing-along from Meloy’s first word. However, much of the second set was heart-heavy, and at times dreary, subdued acoustic material. Gone were the big and heavy hitting moments from the Hazards portion of the show. In the end, the band closed appropriately with a cover of the acoustic-to-rocker gem, Heart’s “Crazy On You.”

While the second set did suffer, I don’t even know if switching the sequence would help the show’s consistency. At some point, The Decemberists will have to start incorporating new and old material into a single set, and that’s a shame because Hazards of Love works so well as a single piece.

Still, The Decemberists were in top form all night long on both sides of the loud/soft coin, and that’s promising for whatever U-Turn the band takes next.