All five members of Brooklyn’s Caveman appeared onstage Saturday at the Miller Lite stage wielding red party cups. Their blend of post-Shins hangover rock is spirit-soaked and instantly appealing.

Every song a B+, nothing was the same. Synths harmonized, guitarist Jimmy Carbonetti dressed for Texas in a bolo tie and tucked dress shirt. It’s iPhone dock rock for Blue Apron nights–subtle, tight bass lines, airy percussion.

Matthew Iwanusa of Caveman plays the Miller Lite stage at ACL Fest weekend on Saturday October 1, 2016. Dave Creaney/AMERICAN-STATESMAN

“Change my mind just to see what’s new,” singer Matt Iwanusa declared on “Never Going Back.” It’s an apt description for a band that’s gone from singer-songwriter twang to churning would-be arena rock.

The band is doing two ACL weekends on the backs of this year’s “Otero War,” the third record. It’s smartly planned, immaculate work produced with just the right amout of veteran bite. Live, that meant drums that pummel on recent songs like “Life or Just Living.”

“War” is concept album about battle-ending archaic devices, set in a dystopian future. But given the 1:30pm early arrival, Caveman spent its set as tone-setting entrance music for wiped travelers who just had their Vitamin water bottles filled with vodka emptied out. Fans aligned the stage barrier less out of enthusiasm, and more because when you lean against the metal, there is less weight on tired legs.

“Nice!” a man to my left routinely said after songs. A more measured and apt compliment I can’t muster.

“In the City,” with its romantic optimism and late-period U2 sludge tempo, was an honest appeal to humanist transcendence. But despite Vance Bedford’s troubling turn as Longhorns defensive coordinator, his uneven set on-screen at the adjacent beer tent drew more visceral replies from a bigger crowd.

“Thank you so much for coming out,” Iwanusa said. “Momentarily, I’ll be in bed.”

You just took a Fasten here, these poor bastards flew in for this.