For three consecutive Octobers, Charley Lau sat in the Kansas City Royals' dugout as the hitters he had so patiently coached—George Brett foremost among them—lost the American League play-offs to the New York Yankees. Next week, if all goes as expected, the Yankees and the Royals will meet again for the pennant. This time Lau will be in Yankee pinstripes—and feeling, perhaps, like a father watching his children fight.

Both clubs have warm feelings toward the 47-year-old batting coach. Brett believes he would never have come close to hitting .400 if Lau hadn't taught him a new stance seven years ago. This season Lau has worked intensively with New York shortstop Bucky Dent and catcher Rick Cerone, and both have raised their batting averages 40 points over last year. "Charley is the most scientific teacher I've ever seen," says Yankee first baseman Bob Watson, a lifetime .300 hitter. "If I'd had a Charley Lau seven years ago, I'd be a much better hitter today."

Curiously, Lau himself was never a man to inspire fear on the pitcher's mound. In 11 major-league seasons, from 1956 to 1967, he hit a mere 16 home runs while compiling an anemic .255 lifetime batting average. "The question arises not more than 50 times a day," he admits, "how I can presume to tell anyone how to hit .300." The answer is that Lau is a natural psychologist and a penetrating observer of the game. In 1969, when his playing days were over, he was asked to work with the Baltimore Orioles' slick-fielding shortstop Mark Belanger, then hitting only .208. "I kept emphasizing rhythm, balance, preparation and weight shift to the front leg," Lau remembers. "When Mark started to hit, everybody started stening."

Belanger finished the season at .287—a mark he has never since equaled—and Lau moved on to coach in Oakland, then Kansas City. With the Royals he spent thousands of hours videotaping hitters and analyzing swings. He discovered that much batting lore was nonsense, including the old saw that a hitter's power is transmitted through his top hand on the bat. (Lau believes it comes from arm extension and follow-through.) He then formulated his Ten Absolutes of Good Hitting, which are the basis of his new book, The Art of Hitting .300 (Hawthorn, $7.95).

Despite his success, the Royals fired Lau after the 1978 season, supposedly for turning the team's sluggers into singles hitters. Though he was hired immediately by the Yankees, the episode, coupled with lingering legal conflicts from a 1969 divorce (he has four children by his first marriage), aggravated a long-standing drinking problem. "He worries about the players too much," says his second wife, Evelyn, owner of a Marathon Key, Fla. sportswear shop. Then last winter Lau went on the wagon. "Evelyn said, 'You're ridiculous,' and that was enough for me," he said. "I quit drinking in one day."

Lau's only weaknesses nowadays are for ex-Oriole Boog Powell's conch chowder, Pavarotti records and hitters who ask for his help. "More and more teams are adopting his ideas," says former Oakland catcher Dave Duncan. "Yet the most amazing thing about Charley isn't his ideas. It's that he convinces you you're capable of doing things you didn't know you could."