Like an innocent child among 39 guilty brothers, Herschel Walker eyes the plastic turf as the head of the household, Coach Chuck Fairbanks, effects a fit.

"That's the fifth time we've run this play!" screams Fairbanks. "And we'll do it until we get it ab-so-lute-ly right!" Fairbanks turns his head slowly so all may see his cold eyes. He betrays, momentarily, a contempt for the bumbling enterprise that is the New Jersey Generals.

The prospect of practicing here until dark can gladden no one. It is a cold, gray day, and the air lets no one forget that Giants Stadium sits on the soft meadow earth that was once an area strewn with pig farms, what is now a forest of industrial smokestacks spitting smoke into the wind.

So this is the glamor of professional football?

No, this is Herschel Walker's new job: to play for one of the worst teams in a new league, to be, as he says, a "pioneer."

There are no matters of life and death involved, not remotely so, but in terms of professional football, Walker has done something of great moment.

He has sacrificed, at least for the time being, the opportunity to prove himself the best at what he does.

While he was running for 5,259 yards in three seasons out of the Georgia backfield, many thought Walker would become the greatest professional running back ever. Better than Simpson and Brown. Better than Grange and Sayers. Better than anyone else.

Five million dollars will go a long way toward putting to rest any doubts Walker might have that he erred in leaving Georgia before completing his fourth year of school to sign on with the U.S. Football League. Yet Walker himself, who was anything but confessional in an interview today, says, "Money is money. It's not life." Nor is it reputation.

Baseball players generally have great knowledge of the history of their sport--the records, the individuals, the technical minutiae and percentages. Walker admits to no such obsession with football, and whether people decide to compare him with the great running backs "is their business."

"I never read any of the stuff that's written about me," he says in his high-pitched drawl. "I reckon I know myself better than anyone.

"I never think about football much. I like to play, that's all. I don't go dreamin' about it. When I was young, football was never something I got into. I still don't watch it on television. I may watch a play or two, and then I'll turn something else on. I just like to play."

Perhaps, it is that temperament that governed Walker's decision. Certain more obsessive personalities, like that of Pete Rose, for example, would never be able to shrug off the question of inferior competition.

If he gains 200 yards against the Washington Federals here Sunday (WJLA-TV-7, WJZ-TV-13, 1:30), Walker will have done so against an aging defensive line and suspect linebackers. The truth is, the defensive competition does not get too much better than that in the USFL.

"I just want to be the best I can be," Walker says. "I don't know what I can do for the league. I don't know what people will say about anything. I just peform."

Walker is used to competing in some of the biggest games college football has to offer--Georgia-Florida, the Sugar Bowl for the national championship. Now he is getting used to slipshod games played before marginal crowds in a new league.

"That doesn't bother me, either," he says. "It's still competing. In high school I played in front of 1,000 people and it felt the same. I'd do it just to play, even if there was nobody in the stands. I'd still play the same."

The closest parallels to Walker's signing with the USFL are Joe Namath's signing with the New York Jets of the American Football League in 1965 and Julius Erving's signing with the Virginia Squires of the American Basketball Association in '71.

But the AFL and the ABA--as competitive leagues, not as video games--were superior to the USFL at the time of those signings. In his fourth year, Namath's Jets won a Super Bowl. With the Squires and Nets, Erving was playing against and with some of the best players in basketball--Rick Barry, David Thompson, Artis Gilmore.

If Walker remains with the Generals, he, too, may see the day when he and his teammates upset an NFL rival in a More Super Bowl. That day will be long in coming, though.

In the meantime, Walker plays in a competitive vacuum.

Even the physical difference between him and his teammates is telling. Walker's sleeves and pants legs appear draped across bridge cables and his neck--well, his neck is the most notable bit of American anatomy since Betty Grable's legs. Yet he is surrounded by tackles who are a little too narrow, quarterbacks who are a little too old.

Ever since his controversial signing, Walker has been reticent in interviews, repeating stock, sometimes monosyllabic answers, fending off all questions about his future.

"My way has always been to block out everything. That's a gift God gave me," Walker says. "If some people feel one way about me, or want me to do this or that, that's their opinion. People are people. I'm not going to try and make everybody happy."

Walker's teammates have been more than happy with him.

"At first, we were all in awe of Herschel," says wide receiver Larry Brodsky. "It was just something to shake his hand. I mean, here was the guy that people were saying was going to be the best football player of all time.

"But I've gotten to know him. He's found a home here. Financially, competitively. He seems pretty content. But who knows? He may have his mind on the NFL later on."

In his first three games, Walker gained just 65, 60 and 39 yards. In the past three weeks, however, he has gained 97, 177 and 133.

Although the league is depending on him to be its greatest star--and his recent play promises he will be--Walker may be one of the most withdrawn personalities in football. His recent marriage was private, and in the locker room he is nearly retiring.

Walker is, in a way, still a 21-year-old from Wrightsville, Ga. By blocking out enough of the outside noise, he is trying his best to live what he calls "a normal life."

"I'm next-door neighbors with Herschel," says guard Wayne Harris. "We're friendly but he's got so much to do. If he goes out anywhere, people come after him. So he stays to himself. He has to. That's his life now."