From Genuine Emotion to Show Biz : Concert: Once again Billy Joel, the consummate entertainer, gives his fans a good show, but he fails to challenge them.

Billy Joel did a shtick early in his show Saturday at the Los Angeles Sports Arena--the first of five sold-out dates there--in which he pushed his piano stool back with his foot as he played a little rock-a-boogie introduction to “Angry Young Man.”

Eventually the stool was just . . . far . . . enough . . . away that he couldn’t quite reach it to pull it back. With a little stagy flair he stretched with his left hand to try to grab the stool, all the while not missing a note with his right hand.

Of course, there was no real point to this exercise, but it was a nice little bit of show.

It’s also a pretty good analogy to the nature of Billy Joel the artist. Often he has tried to give the impression that he’s stretching, reaching, finding new vistas. Some examples--highlights of a nearly 20-year recording career--were presented throughout the two-hour-plus concert Saturday, notably the social observation of “Only the Good Die Young,” “Allentown,” “Out of Saigon” and the new, glasnost -inspired “Leningrad.”

In the end, though, it’s just show. It doesn’t add up to much, any more than the post-World War II names and places listed in the recent smasheroo “We Didn’t Start the Fire” add up to anything besides a list.

Ask yourself: Has ever there been a figure in popular music as successful for as long as Joel who has left so little impact on the music world? Can you name one significant artist whom Joel has influenced? Can you identify any special nature to Joel’s artistic vision?

But to some extent it’s a moot point. “We Didn’t Start the Fire” was a smash hit, and it brought the crowd (predominant age group: mid-to-late 30s; average status, from appearances: comfortable) to its feet. And there’s the rub.

It may have been just a show, but it was a really good show. Joel is a consummate entertainer, a naturally feisty presence and a born ham. And, most important, he knows his fans and plays to them with the best. He just never tests them or challenges them. Or stretches them.

He just delivers, on an uncluttered, unobstructed stage, with nifty lighting and an accomplished (though musically anonymous, save for ace drummer Liberty DeVitto) seven-piece band. He plays most of his many hits, he mugs and clowns, he makes engaging hey-I’m-just-a-working-Joe patter. It’s very easy to sit back and just enjoy.

Too easy, and that’s the problem, just like the facetious, let-’em-eat-cake joke that he closed the evening with:

“If you abso-tively, posi-tootly have to go home,” he told the crowd after cautioning against drinking and driving, “do what I do. . . . Go in a big limousine.”

Way too easy.