Under theatric fuss, Jonases actually rock

MANSFIELD — A lot has happened in the year since the Jonas Brothers last played the Boston area. Nick started an anticlimactic adult-contemporary solo career, Joe began and ended a relationship with fellow Disney star Demi Lovato, and Kevin turned into a married man. But the biggest change evident last night at the Comcast Center (where they played the first of two nights) was in the show itself, scaled down from the arena-spanning multiple stages and full-throttle spectacle of the TD Garden to something more like a straightforward rock show.

The transformation wasn’t a complete one, given that the performance was half concert, half semitheatrical preview of “Camp Rock 2,’’ the Jonases’ upcoming Disney Channel movie. A sizable chunk of the songs came from the soundtrack. Nick sped through the antsy, Jason Mraz-like “Introducing Me’’ in an effort to cram the song into 2 minutes and 15 seconds. “Wouldn’t Change a Thing’’ was the type of duet (between Joe and Lovato) where the singers were more aware of the audience than each other.

While the non-“Camp Rock’’ material had plenty of stadium-size bombast, most of it seemed grounded in the actual music. Many of the songs, like the heavy glam-pop shuffle “L.A. Baby (Where Dreams are Made Of)’’ and the upbeat ’80s-prom-theme-styled “This is the Night,’’ seemed as though everything was cranked to full. Others had a jittery, overcaffeinated feel that made it so the audience’s only recourse was to start jumping.

But the Jonases came on strong with the sleek, effortless “Paranoid,’’ an unsubtle yet high-impact cover of the Beatles’ “Drive My Car,’’ and “Lovebug,’’ which transformed from a happy jaunt to almost Queen-like majesty. The movies might fuel the machine, but the Jonas Brothers aimed to make the ride a smooth one.

Lovato’s opening set was similarly split in two. The first half was given over to her strong solo material, and combining twin acoustic-to-electric songs “Falling Over Me’’ and “Don’t Forget’’ was a smart masterstroke. She became a lot less interesting once she shifted from the Lovato show to the “Camp Rock 2’’ live tour, complete with lakeshore backdrops, headset microphone, and full-cast choreography.