The main stages in Union Park kicked off at 3:30 Friday afternoon with EMA, the latest project from indie-rock veteran Erika M. Anderson, formerly of Amps for Christ and Gowns. The crowds were slow to filter in—unusual, compared to Pitchforks past, but the line on Ashland Avenue was reportedly epic—and the guitarist and vocalist seemed a bit frustrated to be playing into a relative void.

Not that the songs from “Past Life Martyred Saints” translated particularly well in the vast expanse of the ball fields and under the bright afternoon sun.

Wearing a giant “Ema” necklace and fronting a four-piece lineup, Anderson tried to put her spin on My Bloody Valentine’s walls of guitar noise and waves of crescendos. But there simply wasn’t enough power behind the group’s attack to make it feel much more than half-hearted, and the quieter moments in the dynamic ebb and flow just got lost.

As a twist to this year’s account, in homage to the often inscrutable, unjustly monolithic, but nonetheless trademark Pitchfork Webzine rating system, what say we adopt that tact to sum up the sets we experience?

Rating for EMA: 3.2.

Much more exciting was the next act on the second stage, which managed even to overcome significant sound bleed from Battles across the way. Merrill Garbus of tUnE-yArDs is, quite simply, a magnetic and undeniable performer. She seemed a bit nervous during a hasty soundcheck in front of the already assembled crowd—“It’s like you’re seeing me get dressed!” she joked—but a faulty bass head and the sound problems were overcome by the time she launched into “Gangsta,” one of the standout tracks from her stellar second album, “w h o k i l l.”

Part of the fun is watching the Oakland-based singer and songwriter build her loops onstage, electronically layering vocal harmonies and polyrhythmic drum patterns, augmented on this tour beyond her old one-woman shows with the addition of a three backing musicians, most notably on horns. But the technological gimmickry really is secondary to the strength of her songs—so obviously a deeply informed and very loving homage to African music, as opposed to the cheeky cultural imperialism of Vampire Weekend—and the power of her enormous personality, which shines with every note she sings and plays.

And yeah, I’ll say it: She’s so great, she even makes you forgive the ukulele.

Rating for tUnE-yArDs: 9.2.

The polar opposite of Garbus in terms of personality, Sonic Youth legend Thurston Moore had an even harder time than EMA generating any excitement back on the main stages. No surprise, given he was highlighting the material from his recent acoustic album “Demolished Thoughts,” playing the soft-strumming, mumble-crooning troubadour while backed by violin and harp. (Yes, harp.)

Aside from name recognition, it’s hard to explain the logic of putting Moore on a primary stage with this kind of material at 5:30 p.m. There’s no kind way to say it: The set was a snooze-inducing bore, the most interesting aspect of which was the sound bleed (coming from the second stage to the main stages this time), producing unexpected juxtapositions of Thurston chamber music and Curren$y hip-hop.

Rating for Thurston Moore: 1.3.

PITCHFORK 2011 IN THIS BLOG:

July 14: Here we are now, entertain us.