Classic rock (which is really a radio format, not a musical genre) is a strange animal, which has spawned an audience that apparently cares more about hit songs and memories than about who’s actually onstage.

Styx has been improved by its latter-day personnel changes.

By Brett Milano

Thursday night marked the first of many ‘70s-centric bills that are headed for the Blue Hills Bank Pavilion this summer, turning the place into a living classic-rock playlist. Doing the honors this time were Styx, Foreigner and former Eagles guitarist Don Felder, who between them played exactly one song (in Felder’s set) less than 30 years old. So what the hell was local power-pop artist Corin Ashley doing here?

Same thing everything else was doing: Having a little fun and reconnecting with some music he freely admits to loving. Ashley got called in by WFNX’s Chachi Loprete to open the show; he wound up playing all of four songs solo acoustic while the crowd was just starting to dribble in. Can’t say he didn’t grab the moment, though; as he managed to generate a singalong with his second number—a nifty British Invasion update whose title, “Badfinger Bridge,” reveals its inspiration. Ashley has what they used to call a radio voice, the kind of high and forceful one that used to jump out of the airwaves—and still would be if more programmers were paying attention. And lest you think he’s too hip for this sort of show, his first words when I cornered him after the set were “Man, I just gotta meet (Styx guitarist) Tommy Shaw.”

Classic rock (which is really a radio format, not a musical genre) is a strange animal, which has spawned an audience that apparently cares more about hit songs and memories than about who’s actually onstage: Case in point: For the first chunk of Foreigner’s set, not a single person onstage had anything to do with Foreigner’s hits or anybody else’s. Founding guitarist/main songwriter Mick Jones has been the one consistent member, but he’s been having health problems and no longer makes every gig; everybody else in the current lineup joined long after the hits dried up. And nobody in the near-full house seemed too disgruntled when a band of ringers stepped out to open the set with “Double Vision” and “Head Games.” But Jones’ health is improving and he joined the band 20 minutes into the set, and livened things up considerably; playing some loose-cannon solos that put some grit into the mix. Bringing out a Brockton High School choir for “I Want to Know What Love Is” was a nice touch, but miking them would have been even nicer. The encore of “Hot Blooded” was enough to stir whatever adolescent hormones this crowd had left.

Don Felder isn’t the first good musician to get kicked out of the Eagles, but he’s the first to write a tell-all book (Heaven and Hell: My Life in the Eagles) and a few nasty songs about it. (The story in a nutshell: You don’t go asking Don Henley and Glenn Frey for more money). On Thursday Felder played a new song, “You Don’t Have Me,” that was clearly a poison-pen letter to his ex-bandmates. So it may seem strange that he otherwise played an all-Eagles set, doing songs largely associated with the two guys that sacked him. He did feature songs he co-wrote (the music to “Hotel California” was his), but not entirely: He also did “Witchy Woman” which was recorded before he joined. There’s a reason Felder never sang much in the Eagles; his voice is serviceable but not frontman-distinctive. On the other hand, he’s far and away the best guitarist the Eagles ever had—and yes, that includes the burned-out Joe Walsh—so hearing the proper solos was enough reason to haul out “One Of These Nights” and “Life in the Fast Land” one more time.

The latter-day personnel changes has actually improved Styx: They parted awhile back from frontman Dennis DeYoung, who was to blame for most of the hit ballads, and they no longer bother playing them, so no “Babe,” “Best of Times” or “Don’t Let It End” in the set. Instead they’ve gone back to their original sound, sort of a middlebrow, Midweatern take on British prog rock. As played on Thursday, their 1972 debut hit “Lady” still sounds like the Hollies on steroids, which is a good thing. Lack of their frontman has apparently given Styx a sense of purpose—they’re underdogs, so they work harder—and they’re good-natured about the nostalgic role they serve for their fans. In the night’s best bit of stage patter, singer/guitarist Shaw pointed at the audience and said “You’re out there trying to look all grown-up and respectable…but I remember you.” And in a weird bit of synchronicity, a fully-uniformed cop walked past me, singing along with the words while Shaw sang about running from “the long arm of the law” on “Renegade.” It was the kind of set that makes the classic-rock zone a fun place to visit, whether or not you really want to live there.

Brett Milano has been covering music in Boston for decades, and is the author of Vinyl Junkies: Adventures in Record Collecting (St. Martins, 2001) and The Sound of Our Town: A History of Boston Rock & Roll (Commonwealth Editions, 2007). He recently returned from New Orleans where he was editor of the music and culture magazine OffBeat.