FOR SIX YEARS, 1961-66, Koufax was the most commanding pitcher in baseball–and those six years were enough for the editors of Sports Illustrated to name him their favorite athlete of the 20th century. Only four other pitchers have averaged more than a strikeout per inning; no other pitcher has led his league in ERA for five straight years. Three seasons with 25 or more wins, four no-hitters, one a perfect game, the youngest player ever inducted into the Hall of Fame … Enough? Koufax retired too soon–he was only 30–to put up the career numbers of a Walter Johnson or a Nolan Ryan, but he went out in style: in his last year with the L.A. Dodgers, he was 27-9 with an ERA of 1.73. Why would anyone retire after such a year? Because he was in too much pain to continue: he plunged his overworked left arm in icewater after every game, popped codeine and Butazolidin (an anti-inflammatory drug for horses that’s now off the market) and smeared on Capsolin, a near-toxic concoction made from chili peppers. (A teammate once put on one of Koufax’s sweatshirts; his skin blistered and he began to throw up.) Had Koufax not quit when he did, he would have lost the use of his arm.

But as Jane Leavy makes clear in her splendid new biography, “Sandy Koufax: A Lefty’s Legacy,” his statistics don’t begin to explain the mystique. For one thing, he was insanely good-looking–like Gregory Peck crossbred with a Greek god, according to one description–and physically imposing: he stood 6-foot-2 and could hold half a dozen baseballs in that left hand. For another, of course, he was Jewish; the game he didn’t pitch–the opener of the 1965 World Series, which fell on Yom Kippur–did far more to make him a celebrity than the perfect game he’d pitched against the Chicago Cubs a month before. And most tantalizingly, he refused that celebrity, both before and after his retirement. As Leavy astutely points out, Joe DiMaggio marketed his reclusiveness; Koufax has simply declined to play the fame game at all–not even in the ostentatiously negative manner of a J.D. Salinger. Both he and his friends–of whom there seem to be many–insist that he’s not a recluse. One childhood friend from Brooklyn calls him “a privatist”; the great Dodgers announcer Vin Scully calls him “a minimalist. To say the least.”

True, according to Leavy, he didn’t bother to read that Sports Illustrated cover story that named him athlete of the century. True, he quit a career in broadcasting because “I didn’t want to die in a cheap motel.” True, he tried to talk Leavy out of writing her book. But he’s worked, officially and unofficially, as a pitching coach (such stars as Ryan, Don Sutton, Orel Hershiser and Al Leiter consider themselves disciples), does one autograph show a year to keep himself solvent, shows up for such events as benefits for pediatric AIDS and even fantasy camps. Good story there. Recently a camper stood up to bat against him and said, teasingly, “Goddamn it, Koufax, is that all you’ve got?” “I mean to tell you,” says an ex-major leaguer who saw it happen, “his eyes changed like that. He threw four or five pitches there’s no doubt in my mind were on the verge on 90 miles an hour.”

Koufax only had two pitches: his terrifying fastball (“Fifteen feet from home plate,” one victim recalls, “it got an afterburner in its ass”) and his equally terrifying curveball, which appeared to drop two feet; the first time one rookie caught him, he stood up to catch a Koufax curve and it hit him on the knee. He was able to accomplish all this because he had probably the most perfect mechanics of any pitcher in history. Hershiser once spent three months practicing nothing but Koufax’s method of wedging his back foot into the rubber; his drawings of the ideal pitching motion, Leavy writes, “circulate through baseball’s underground, accompanied by the whispered awe usually reserved for great art.” One biomechanical researcher recently performed a computer analysis of Koufax’s delivery, and concluded that “there was absolutely not a wasted piece of energy.” He also studied the opposition. Once, in the mid-’80s, when Koufax had been retired for 20 years, he was at an old-timers’ game and overheard Billy Williams, Lou Brock, Willie Stargell and Willie McCovey wondering how many home runs they’d hit off him. “Sandy, right away, says ‘I’ll tell you’,” Williams recalls. “So he pointed to me. ‘You hit two, and you hit none, you hit none and you hit one.’ He knew.”

Koufax wouldn’t let Leavy interview him formally for her book, though he helped verify facts and encouraged his friends to talk to her; she ended up interviewing some 400 people. She accommodated his desire for privacy to an extent that would make a more conventional biographer feel compromised. She honored Koufax’s request not to interview his closest relatives and chose not to talk to any of his old girlfriends, either of his ex-wives, nor to “the woman who currently shares his life.” Yet after reading the book, you can’t help but agree with her that “you don’t need to know everything to write the truth.” Sandy Koufax is a product of a recent, but almost wholly different time, before money and celebrity almost inevitably trashed personal dignity. In his rookie year, 1955, Koufax was also going to architecture school at Columbia–and asked his professor’s permission to skip class so he could attend the Dodgers’ World Series victory party. Ten years later, after going 26-8 with a 2.04 ERA, he asked the Dodgers for $167,000 a year for the next three years–and they threw a fit. “Those who’ve known him longest,” Leavy writes, “say he hasn’t changed at all.” If the game, the culture and the world have changed–so much the worse, for all of us.