THE BEST THING about Howard Cosell's book Cosell is that his grating voice is not a part of it. The worst is that, as the title suggests, the focus is on Cosell himself, rather than on American sports seen through his eyes.

Only in two sections does Cosell transcend himself and write informatively about something else. Carpetbagger sports owners are the subject of one of these parts, heavyweight boxing--with emphasis on Muhammad Ali--of the other.

Cosell apparently values his wit more than any other quality, and his book gives him a chance to display it in all its dismalness. For example, he recalls the time he and his "Monday Night Football" co-star, Don Meredith, were visiting the Detroit Lions' training camp. Near them was Bobby Williams, a black member of the team. "Suddenly I turned to Williams," Cosell writes, "and said, 'You know, of course, that Meredith has no use for you black players."'

Meredith "became crimson and said, 'What's that?'

'"Don't play the innocent line with me, Don,' I shot back. 'Everybody knows."'

On another occasion, "I acquainted every attractive young woman within sight with handsome Frank Gifford. 'Look at him standing there, girls,' I would announce. 'A veritable Greek god. America's most famous football hero. The dream of the American working girl. The single most sexually dynamic man in the chronicle of the male sex. He's in room nine-fourteen...'"

Apparently, Cosell responds to boredom or uneasiness by pressuring someone nearby with this kind of needling. He is wrong to confuse this habit with a sense of humor.

Cosell speaks harshly about such sports and non-sports figures as Casey Stengel ("rude, crude and uncultured"), Dick Cavett ("takes himself too seriously"), and David Frost ("totally absorbed with himself"). But his strongest attacks are on sportswriters. In language similar to Richard Nixon's, he writes, "I am not interested in petty feuds with some writers. Let them do their thing, and some have done it to me pretty well."

He snipes at sportswriters several times, typing them as simple-minded hacks who don't understand what's really important in the world. Last spring, he remembers, "the scribes were writing about Aaron's race for Ruth...about whether or not Mays should be playing. Could Oakland do it again? These were typical topics. My own mind drifted to...Curt Flood[,who] had sacrificed his career to fight the reserve clause."

Cosell condemns writers who "travel and eat at team expense, thus defying one of the fundamental laws of journalism and creating a clear conflict of interest." But somehow there is no conflict when he spends a weekend at the home of Don Klosterman, general manager of the Baltimore Colts, or "travels the world" with Walter Kennedy, commissioner of the National Basketball Association.

The basic reason for Cosell's antipathy to sportswriters, I think, is that he lacks confidence in his own writing ability. It's easier to talk and say nothing than to writing and say nothing. Any lack of confidence he has is justified: cliches are abundant in Cosell. People "grab a sandwich and risk ptomaine poisoning." A fighter "figured to have two chances: slim and none." So-and-so is "all man." A TV show's success "is now history." And, in a class by itself: "Reporters clung to [Ali] as flies are attracted to a wet jelly bean."

By far the best part of the book deals with the heavyweight boxing champions since 1956--Patterson, Johansson, Liston, Ali, Frazier, Foreman--and their biggest fights. Cosell offers inside information and for once lets athletes, rather than himself, dominate the action. He recalls a visit to Sonny Liston's training camp during which Liston and Liston's wife danced in the ring to the song "Night Train." He discusses Ali's poor conditioning before his 1972 title fight with Joe Frazier and before his bout last spring with Kenny Norton.

Cosell effectively blasts the myth that it's hard to find a black man qualified to manage a major league baseball team. "Any 12-year-old," he writes, "knows that all [owners] do is play musical chairs with a bunch of anonymous mediocrities as managers...there are certain preeminent qualifications to managing a major-league baseball club: You must be white and either a heavy drinker or a cardplayer."

SOONER or later, however, Cosell always returns to his main interest: himself. He congratulates himself for his grueling schedule--as if he performed a vital service--and is impressed by his "great verbal dexterity." He recalls with pride different occasions when he badgered athletes into being interviewed only minutes before a contest, when they should not have been disturbed.

"Without me you're a nothing," he once told Ali. "Nobody would know your name...Where would you be...without me doing your fights...? Yes, I made you." Trying to interview Sandy Koufax on short notice, he says, "Sandy, you were just a damned snit from Brooklyn sitting in the corner of the dugout surrounded by the great ones when I first met you. You owe me this."

Cosell seems to approach everything with the attitude that he has something to teach rather than learn. But the expertise he brings to boxing, where the fighter's personality is crucial, cannot be carried over to a team sport like football, where personalities are less significant than the always changing, always unique situations of the game. Yet on "Monday Night Football" each week, Cosell subjects viewers to trivial "color" stories--stretched out inexcusably--while the game itself becomes a backdrop for his voice.

In his book, Cosell's perspective about himself is revealed best by his dead-serious statement that "the one thing that would take me out of broadcast would be the opportunity to serve in the Senate of the United States." Serve--or perform? But maybe this idea isn't so far-fetched. Watch "Monday Night Football" tonight, listen to Cosell, and then consider whether a promise like that might not get him elected.