But it's also largely due to the presence of the Roots, the dazzlingly versatile musicians who could entertain a half-million people for three hours on their own, thank you, but who are equally happy to act as an unparalleled backing band and make artists like Potter sound better than they have before, as the leggy singer surely did on a cover of Led Zeppelin's "Whole Lotta Love."
The everything-improves-with-the-Roots rules also held true for Hayes, the perky 21-year-old who had the combat duty of replacing teen pop star Demi Lovato, who pulled out Wednesday. No worries. The Roots had the kid's back, and he threw in a karaoke cover of the Police's "Every Little Thing She Does Is Magic" just to make sure the crowd knew one of his three songs.
Mayer, too, was smart enough to play to his strengths and the Roots', with the mellow, bluesy grooves of "Something Like Olivia" and "Queen of California," on which his guitar and that of the Roots' Kirk Douglas worked themselves into a satisfying tangle. Almost enough to forgive Mayer for his ode to passivity, "Waiting on the World to Change."
With the VH1 broadcast, this year's Jam was all about national outreach and demonstrating that Philadelphia is the musically cool place to celebrate the day. (Compared with, say, Washington, where Barry Manilow was the pre-fireworks entertainment.)
In the early stages, though, the show was thoroughly Philadelphian. The Roots kicked off in high-energy mode with the unstoppable riff of Cody Chesnutt's "The Seed (2.0)," part of a medley that included the surf guitar rocker "Apache" and Kool and the Gang's "Jungle Boogie."
The band theven brought on the show's host, Philly-born comic Kevin Hart, who after screaming out "I'm home!" three times had the crowd, which he estimated to be "about five million," sing him Stevie Wonder's "Happy Birthday." (He turns 33 on Saturday.)
Hart then brought out Scott. The North Philly native's set, which started with the earthy soul workout "It's Love," stretched through two commercial breaks. For the crowd on the Parkway, the rhythm of the evening was rocky due to those breaks.
But Scott did her best to keep her hometown crowd happy, fitting in a version of "Blessed" while the cameras were not rolling.
As adept as the Roots were at backing everyone else, the concert could have done with a few more segments focused on them. One such interlude that played like a hip-hop history lesson beginning with Kurtis Blow's "The Breaks" was painfully brief. A shame, because it brought the crowd instantly to its feet.
Contact Dan DeLuca
at 215-854-5628, firstname.lastname@example.org, or follow on Twitter @delucadan. Read his blog, "In the Mix,"