KROQ’s holiday slay ride

Here are two ways to fall into a crowd, demonstrated Saturday at the Gibson Amphitheatre at the first of two nights of the annual KROQ Almost Acoustic Christmas: Pete Wentz, bassist and main writer for the Chicago-based band Fall Out Boy, stepped forward and trod upon the outstretched hands of the crowd crushing the stage. Literally elevated by admirers, he struck a satisfied pose, a character fleshed out by the connection with his fans.

An hour or so later, Brandon Boyd, singer for Calabasas’ own Incubus, dived in another direction. At the end of a typically spacious jam, he simply fell forward, like a surfer entering a wave. He didn’t stay with the crowd as long as Wentz did, but in some ways, he got closer.

These different methods of personal space invasion could be read as a metaphor for two strains within alternative rock today. On the ascent, there’s the emo-punk of bands such as Fall Out Boy, which is all about young men telling stories that release their angst and distinguish them within the crowd. On the other, there’s the slightly more old-fashioned, jam-based fusion of such post-grunge groups as Incubus, which puts groove and sonic texture before melody and narrative, subsuming players’ personalities within a high-flying feeling of transcendence.

Radio-sponsored shows like this annual charity event highlight the ideas currently taking hold in the rock world; this night, it was all about glitz outdistancing groove. The Almost Acoustic Christmas, like an office party for the Los Angeles alt-rock scene, takes place over two nights and features bands that have found success, at least partly due to KROQ’s airplay, during the year.

The bill Saturday included newcomers (Saosin, Wolfmother) and vets (Papa Roach, Foo Fighters), but the night belonged to three bands hitting their stride: Fall Out Boy, whose album due in February is the first hotly anticipated rock release of 2007; Incubus, whose just-released sixth album is No. 1 on the national sales chart; and My Chemical Romance, whose ambitious disc “The Black Parade” is the year’s most-lauded rock album. Of those bands, only Incubus focused more on internal connections than on its show.

Fall Out Boy vaulted into its set with a manic energy that felt almost staged but was borne out in rapid-fire songs. Patrick Stump, the band’s singer, spat out Wentz’s lyrics in a hearty tenor that carried each song’s melodicism through the barrage of hard-core riffs. Each song expressed the sexual angst and self-doubt of boys banging on the door of manhood (“We’re losers,” said Wentz at one point, contradicting reality), and the teens who made up half the crowd unceasingly yelled along. The band is trying new musical templates -- its new song, “This Ain’t a Scene, It’s an Arms Race,” sounds like the pop-wise child of the late, great feminist punk band Sleater-Kinney. Now, those are some shoes it takes guts -- and serious chops -- to fill.

Incubus has often stepped into big shoes too, modeling its sound partly on Pearl Jam and partly on the Red Hot Chili Peppers. The group has matured into its influences, although Boyd’s delicate presence -- he seems to want to retreat into his band’s rhythms -- downplays his appeal as a frontman.

What’s most interesting about Incubus (aside from the fact that it’s one of those bands with more hits than you remember, as proven by the ecstatic engagement of Saturday’s audience) is its blend of turntablist flourishes, gently funky bass lines and shredding guitar; Boyd’s gentle voice crowns this combination, not asserting huge personality. The adults in the crowd responded excitedly to Incubus’ hard-rock meditations, which didn’t reach out to the kids the way Fall Out Boy’s did.

My Chemical Romance didn’t quite reach out, nor did the group lie back into mellow musicianship. Instead, it recast the classic rock spectacle in the shiny colors of emo’s glam attitude.

Featuring songs from their challenging, captivating latest effort, “The Black Parade,” members of the New Jersey-based group bounced across the stage with the bright charm of Broadway stars -- especially singer Gerard Way, whose fluttering “jazz hands” and coy poses recalled none other than “Rocky Horror Picture Show’s” Frank-N-Furter (as played by Tim Curry, of course). Compellingly campy, My Chemical Romance brought an urgency to its songs that fully delighted the crowd.

A few acts tried to steal the night from these rightfully featured bands: 30 Seconds to Mars played a set that sometimes veered into heavy melodrama, but its leader, actor Jared Leto, proved a ridiculously entertaining showman, spending a big chunk of time wandering through the set like a televangelist, mike in hand.

If his songs had been stronger, Leto might have walked away with the show’s MVP award. Instead, that went to Davey Havok of AFI, who led his band through an elegant, blazing set of goth-kissed post-hard-core anthems.

Dressed all in white (like his bandmates) and jumping gymnastically among several platforms, he was a showman who never forgot to project the primal spirit of rock. More grown up than the emo-punks, more focused than the jammers, AFI cultivated a key strain inherent in rock -- not just glam but also glamor. This way, the San Francisco band found its path to domination.

ann.powers@latimes.com