279 pages. $6.95

THE "As told to ..." form of sports biography is, by its very nature, a literary genre with a planned obsolescence. Its selling appeal exists only as long as the popularity of the athlete it portrays, and because of the style barriers that are necessarily imposed upon it, its literary worth is severely limited.

If one adds to these restrictions a subject whose controversial popularity automatically reduces the size of the book's potential readership, it seems hardly worthwhile to even bother writing it. But the financial rewards, if only temporary, can be considerable; the case and rapidity with which a collaborated autobiography can be put together are tempting. So it is not surprising that Dick Schaap, a well-known freelancer, has undertaken an "As told to..." book about New York Jets' quarter-back Joe Namath. And it is also not surprising that his effort falls short of its mark, plagued primarily by built-in style barriers.

I Can't Wait Until Tomorrow... Cause I Get Better Looking Every Day makes no attempt to avoid the "potboiler" label. Schaap wrote it at the most opportune time possible-shortly after Namath had silenced his critics by engineering an improbable upset of the Baltimore Colts in the Super Bowl game a year ago-and he consciously played up the personal qualities that had given Namath his notorious charisma.

Television created the Namath legend. The flaky white football cleats. The longish hair. The FuManchu mustache. The perfectly thrown touchdown bombs. And the newspapers, by religiously quoting Namath's reaction to his publicity, did the rest. Overnight, Namath's name became a household word, and the unfavorable reaction to it by the perpetrators of the All-American clean-living school only strengthened Namath's appeal.

Eventually, as it became clear that Namath was also the prime mover behind the Jets' increasing success, the scene was being prepared for his inevitable comedown-when his AFL champion team would be crunched by the NFL powerhouse Colts. The comedown, of course, never occurred. In the best Cassius Clay tradition, Namath brashly predicted a New York victory in the Super Bowl, then had the gall to actually bring it off. Schaap had his book.

But what causes "I Can't Wait Until Tomorrow..." to fall short of its potential is Schaap's hasty effort in writing it. Granted, the time element threatened to make the book outdated if the author delayed longer than six months to have it published. But other authors, John McPhee, for example, have created fairly competent accounts of other athletes within a roughly comparable time span. Schaap's biggest failure, it seems, is that he relied too heavily upon his experience in writing Instant Replay, with Jerry Kramer, in his effort to put together a similar effort on Namath.

The similarities between the two are too obvious, and too well-connected to be coincidental. Instant Replay, another "As told to..." book, explains the crumbling of the Green Bay football dynasty in the late '60's, as seen by Kramer, a then recently-retired Packer lineman and kicking specialist. I Can't Wait Until Tomorrow recounts the embryonic construction of another dynasty, as seen by one of its creator. And Schaap falls easily into the trap of using a parallel style for the latter.

THE CREATION of the basic "As told to..." genre is simple. The author lives with his subject for anywhere from a few days to several weeks, holding lengthy tape-recording sessions during which the subject spills forth everything about his career, private life, and projected future that he can think of. The author returns to his apartment, and in seclusion, edits the tapes down to what he feels is relevant to his needs, and arranges the segments in what would make the most natural order. Then, taking care to capture the "voice" of his subject, he transcribes the sessions into prose, and VOILA! ... the "As told to ..." book. And a blatant potboiler as well.

The method, of course, has several obvious advantages. With a diligent effort, the author can turn out a book in two months, well within the life-span of an athlete's popularity. Since the story is told in an athlete's own words, more or less, it has more direct appeal to an audience that is usually hungry for the "inside stuff" on the athlete. And since the subject himself actually wrote the book, as it were, it can lay claim to being an "official" autobiography-always a valuable asset to its financial success.

I Can't Wait Until Tomorrow has all of these advantages. But after Namath's disappointing season last fall, and the Jets' failure to even regain their AFL title, much less the Super Bowl championship, much of what the book depends upon for readership appeal has vanished. And what is left reads like a post-facto apologia, in which few people still have any interest.

Namath had been subjected to a considerable amount of criticism because of:

his arrogance

his showboating

his neglect of proper training rules

his physical appearance

his tendency to "swing" a little more raucously than is considered acceptable

his knees, which were bad enough to excuse him from the draft, but healthy enough to qualify him as a professional quarterback

his drinking habits

his "excessive" $400,000 contract

his "mouthing off"

his white football shoes

his alleged association with known gamblers

Schaap, apparently, attempted to make his book serve as a sort of Namath's Great Reply to the critics, and the arrangement of chapters alone shows it.

The first, "Harper Valley P. T. A.," explains why Namath felt that his interest in Bachelors III, a tavern allegedly frequented by Mafia-types, was innocent.

The second, "Who'd They Think They Were Messing With. The Rams?" provides the reasons why Namath felt he was justified in predicting the Super Bowl triumph, and goes into detail concerning its attainment. The fifth, "They Probably Would Have Told Our Lord to Cut His Hair," argues in defense of Namath's hair style. Anther defends his large bonus contract. And so on.

What is most irritating about Schaap's style is his blatant pandering to a narrow audience. One chapter entiled, "I Like My Girls Blond and My Johnnie Walker Red," is devoted to Namath, the stud, and one can just imagine the segment of America that fancies itself he-man. Schlitz-drinking, duck-shooting and hard-loving smugly saying, "Yeah, goddamn, Namath's one of US, Fcrissake."

In fact, that same chapter appeared last summer in True magazine, one of your basic rod-and-gun club publications, and on the cover there was a mud-stained Namath sitting in front of a locker filled with a llama rug, a bottle of champagne, and a naked girl.

SCHAAP is obviously a much better writer than one would conclude from the book. His epilogue, which explains how the book came about, and the problems Schaap faced in trying to nail down Namath, is superbly written, and departs noticeably from the Namath-voice that comprises the remainder of the work.

The sports biography, or perhaps, the sports profile, can be an amazingly interesting and worth-while form of journalism. When it is well done, as it is often in the New York Times Magazine, the New Yorker , and surprisingly, Sport Magazine , it can compare with any form of literature with regard to attainment of its avowed goal. John McPhee proved that the profile can successfully be expanded into a book with a piece about Princeton's Bill Bradley several years ago.

But Schaap's unfortunate failure to write I Can't Wait Until Tomorrow , as such a profile, with his own impression in his own words, dooms the book to fall into the same class as Al Hirshberg's Yaz, or Hawk, about former Red Sox outfielder Ken Harrelson, or Mike Holovak's Violence Every Sunday. And who remembers them any more?