Passing the taste test

There was a moment during Saturday’s KROQ Weenie Roast y Fiesta that exemplified its competing impulses to stay true to the values of modern rock -- authenticity, earnestness, boys with guitars and a healthy ladle of angst -- while navigating a pop market that demands freshness, experiment and instant gratification.

It happened just as Rancid’s Lars Frederiksen took the stage during Tim Armstrong’s solo to play Rancid’s mid-’90s hit “Ruby Soho.” Frederiksen ran into guitar troubles that forced Armstrong to change plans. The crowd erupted in pained boos -- Southern California is home for Armstrong’s backing band the Aggrolites, and Rancid’s revivalist hard-core ska still draws a devoted fan base of gutter punks and adventurous reggae heads.

But the audience quickly recovered as Armstrong brought out another friend, the pop nymphet and onetime Britney Spears opener Skye Sweetnam, to shimmy and sing the hook on “Into Action,” a lighthearted and irrepressible two-tone ska number off Armstrong’s solo album “A Poet’s Life.” Was it the most or least punk gesture of the day? The crowd, rightfully, didn’t seem to care -- it was too busy dancing off the afternoon sun at Verizon Wireless Amphitheater.

So goes the breed of loud-but-not-edgy alternative rock that’s become KROQ’s bread and butter in recent years. Save for a few gruesome sets, most of the bill found a comfortable and successful middle ground between pop and punk sensibilities. The Killers, meanwhile, were forced to cancel their appearance, reportedly because of illness.

The dapper Swedish trio Peter Bjorn and John was the most unlikely act at the Weenie Roast. But a hit single plays well anywhere, and the band has a humdinger in the whistle-happy “Young Folks,” which again benefited from Victoria Bergsman’s adorable shyness onstage. Local heroes Silversun Pickups, whose fuzzy post-indie rock is proving to have endless appeal for restless emo kids, played a loose and beery set.

The bottomless well of L.A.’s devotion to melodic punk allows a band like Tiger Army to play an arena and not seem mis-billed. The trio toned down its full-throttle psychobilly into a lean pop act, and country-influenced tracks like “In the Orchard” were unexpectedly moving. Bad Religion needled its usual suspects (environmental catastrophe, words under four syllables) but riled the crowd into a sing-along on the antiwar lament “Sorrow,” fast becoming the “Imagine” of the surf-punk set. Orange County demigod Social Distortion did what it does best -- working-class bar rock that’s almost radical in Mike Ness’ refusal to mess with his winning formula.

Outside of a toothless set of Korn’s long-expired aggro-metal and a stratospherically silly attempt by 30 Seconds to Mars’ Jared Leto to channel both Gerard Way and Chow Yun-Fat on a Chinese-inspired stage set, the main stage embodied alternative radio’s strictures to distinguish your sound within a rigid set of rules. Queens of the Stone Age and Interpol were workmanlike in their takes on flashy stoner-metal and steely post-punk, and a surprise set by Incubus’ Brandon Boyd, Mike Einziger and a 14-piece boys’ choir had an easygoing rapport that benefited from its lack of alt-rock bombast.

Even Linkin Park, one of the last survivors of rap-rock’s turn as the dominant strain of guitar music in the early 2000s, showed a welcome eagerness to try new ideas. Dressed in tight jeans and a leather jacket more Joey Ramone than Jock Jam, Chester Bennington led the band through the swaggering, punk-influenced “Given Up” and the politically charged “No More Sorrow” with the vigor of an artist with something to prove again. Odd for one of the decade’s biggest-selling rock acts, but its eerie synthesizers and Mike Shinoda’s amiable guitar playing went a long way toward reinventing themselves. Just like a great pop band would.

august.brown@latimes.com