So what’s the appeal?

John “Cougar” Mellencamp’s a modest-looking Midwestern dad who’s got a heart attack documented in his medical record, but who’s also got enough orneriness (or foolishness) to keep a pack of smokes in his shirt pocket to this day. The man was never much of a dancer, even in his salad days (if the video evidence can be trusted), and as he coasts into middle-age, he doesn’t even swivel particularly effectively or jump particularly high when he does bother to make an effort to move on stage. Then there’s Mellencamp’s rasp of a voice, which has always sounded like it was one smoker’s hack away from a ripped vocal cord, and which isn’t getting any better with time. Or with cigarettes.

So why, then, were there thousands of people gathered Sunday night at SPAC? Were they there for the black flies? The traffic jams? The hostile pavilion ushers? The humidity? Nope. The crowd came to hear some hits — and, man oh man, with 29 top 40 singles to his credit, the artist formerly known as Cougar has got hits to spare. So on Sunday, we all every one of us heard (and sang along with) “Jack and Diane,” “Lonely Old Night,” “Crumblin’ Down,” “Paper in Fire,” “Wild Night,” “Small Town,” “R-O-C-K in the USA,” “Hurts So Good,” “Your Life is Now,” “Authority Song,” “Pink Houses” and half a dozen others. And they all sounded very, very good, indeed.

Which owes something to the fact that Mellencamp’s got a knack for big-time singalong choruses, but which also owes something to the fact that Mellencamp is smart enough to assemble an ass-kicking band that was able to cover for any and all of his own shortcomings on stage. Interestingly, this seven-piece band defied all stereotypical Smalltown-equals-redneck-equals-bigot-equals-boy’s-club expectations, coming across instead like a contemporary version of Sly and the Family Stone, all gussied out for the Millennium.

There were men and women on stage Sunday night, brown skinned folks and white skinned folks, straights and freaks and longhairs and cowboys alike, all making beautiful noises and motions together on stage. At the bottom-line, it was just an evening of everyday music by an everyday hero for all sorts of everyday people — and there ain’t a damn thing wrong with that, now, is there? (Except, of course, for the fact that you’re thinking about buying a Toyota, but that’s a different rant for a different day . . . )

And if you had been paying attention Sunday night instead of jabbering incessantly during their songs (yes, I’m talking to you), then you would have noticed that Son Volt actually put on a nice everyday kinda set as well. I certainly hope, however, that the Illinois-based quartet have a long sit-down with their management about the sagacity of signing them up for an opening slot on Mellencamp’s tour. Singer Jay Farrar’s songs require — and regularly receive, in the proper venues and on the proper bills — some sort of audience focus, lest their subtle charms evaporate unheard beneath the waves of apathy oozing out of another performer’s audience. Somehow, I think that at this stage in their career, a mature band such as Son Volt are better off being adored by 200 people than being ignored by 20,000.