Just like the heyday of Smash Mouth and Sugar Ray, members of the aging bands have come and gone. The staple of a successful band's longevity, however, is not always tied to maintaining the original group of musicians.
Sometimes, the solution is to add a new member to the group: nostalgia.
With a lineup that included Gin Blossoms, Vertical Horizon and Fastball, along with the two aforementioned California-based pop/alternative-rock/ska powerhouses, it was no surprise that a mix of twenty-somethings and middle-aged rock fans packed into Stage AE for the "Under the Sun" tour's stop in Pittsburgh.
In the words of one fan: "It's a throwback to the '90s, man!" Their childhood soundtracks haven't missed a beat.
"Anywhere you go I'll follow you down," sung Robin Wilson, the current lead singer of the Gin Blossoms. The group no longer needed the energy they once possessed to woo the crowd, as tracks like "Follow You Down" earned a roar of approval from the fans, who were far from upset that the band had traded on-stage antics for bald spots.
The fans were just as happy to rock out in their own way rather than jostling for position in the crowd; their own vocal solos could be heard throughout the now-classic tracks played by all five bands.
They may not have been Creedance Clearwater Revival or Crosby, Stills and Nash, but each of the groups has a sizable following that will continue to fill venues for years to come, no matter how far they are removed from their youth.
Judging by the reaction of the crowd when Mark McGrath and Sugar Ray took to the stage, it was as the members of Pink Floyd had put aside their differences and chosen Pittsburgh as the destination for their one and only reunion performance.
"We are Sugar Ray from 1999," said Mr. McGrath before the group performed "Someday." He needed no introduction; his bright white jacket and palm tree-covered button-down shirt were just as eccentric as the band's frontman.
For the next hour, the North Shore turned into the group's hometown of Newport Beach, Calif.
Raising his guitar above his head without any intent to strum its strings, Mr. McGrath dedicated the next song to the Irish, belting out the chorus to the group's 2001 track "Answer the Phone."
"The fear is that long after our hits..." said Mr. McGrath, rattling off a long list of age-related worries as he referenced the nostalgia that brought many of the loyal fans to the show Wednesday night. It was those same fans the five groups relied upon.
"If we get together and build this thing, you beautiful people will come and celebrate," he said, coming close to borrowing a line from "Wayne's World." The celebration that began when the band first formed over two decades ago had yet to stop and the fans continued to party on.
"How about another number one from 1999," said a laidback Mr. McGrath, asking the crowd to join in the chorus of "Every Morning."
Mr. McGrath wasn't the sole focus of Sugar Ray's set though, as lead guitarist Rodney Shepherd led the band in a rendition of the Violent Femmes' "Blister in the Sun" and performed multiple solos.
"You can't have the '90s without a little '80s," said Mr. McGrath.
But soon the set would shift back to the last decade of the last millennia as multiplatinum-selling group Smash Mouth walked on the stage.
"I can't get enough of you baby!" sung the group's frontman Steve Harwell, the inflections in his voice rising to the occasion to bring fans back to a time before Shrek had graced the silver screen.
The hits kept coming, as "Then the Morning Comes" and "Come On Come On" followed the band's hit opener.
Of course songs like "All Star" didn't get left out, as Smash Mouth unleashed their full arsenal on the crowd, leaving them with memories of the '90s fresh in their minds.
Andrew Gretchko: email@example.com or on Twitter: @Andrew_Gretchko