Just as UFOs turn out to be weather balloons or the reflection of someone's nose in his sunglasses, most things can be explained. The day Martians landed near second base at Comiskey Park, we knew Bill Veeck caused it by hiring midgets in rented get-ups. But even as we talk, baseballologists search for an explanation to Fernando Valenzuela, who is the biggest mystery this side of catsup as a vegetable.

"I know what Fernando is," announced Tommy Lasorda, the Dodger manager reborn a genius by sending Valenzuela to the mound, as he will in the National League championship series Wednesday.

"He's an old Aztec chieftain sent down from heaven by Mr. O'Malley because he knew I needed him."

Valenzuela is 20 years old. For doubters, the Los Angeles Times printed a photocopy of his birth certificate. He tied the major league record for rookies by pitching eight shutouts in a 13-7 year. Then, in the miniplayoff, he allowed Houston two runs in 17 innings, winning Game 4 on a four-hitter that left the Astros wondering what spaceship delivered this advanced-evolution pitcher.

"When you get ahead of Valenzuela on the count," said the Astros' Terry Puhl, a very good hitter, "then he'll throw you a pitch that looks very hittable -- until you try to hit it, and then you realize it is a screwball on the low, inside corner."

Ty Cobb wouldn't have had a prayer.

Allowing for the normal bull-feathers quotient in any Lasorda speech, the manager's theory yet is as good as anyone else's. Walter O'Malley, the late Dodger owner, had an indirect hand in the phenomenon of Fernando. On his command, delivered through General Manager Al Campanis, the Dodger scout Mike Brito spent dusty summers prospecting for -- Brito's words -- "a Mexican left-hander, because in Los Angeles we have so many Mexican fans."

The Mexican Sandy Koufax.

Which is like Florence's city council ordering its bird dogs: "Bring us back an Austrian Michelangelo."

Amazing thing, Brito did it.

Three summers ago in Silao, in the state of Guanajuato, Brito saw a 17-year-old left-hander.

"Twice he had the bases loaded and nobody out -- he did not have his control that day -- but he was not disturbed by it," Brito said today. "If he was 17, he looked like a 40-year-old man. He had poise given to him by God."

Brito liked the kid's fast ball. It moved nicely. The curve had good rotation.

"I called Mr. Campanis right away," Brito said, "and I said: 'I think I have found the Mexican left-handed pitcher we're looking for."

Valenzuela's story is the stuff of fables, already told in a quickie book published during the strike. In "Fernando!", by Mike Littwin, we learn Valenzuela is one of 12 children born in an adobe hut in a woebegone farming village, Etchohuaquila, 250 miles below Tucson. Villagers live and die in the huts in which they are born. Only by hearing baseball on the radio did Valenzuela learn the world was more than his hut and a rattletrap bus carrying workers to the farm.

When he was 10, he first picked up a stray baseball from a town game. His friends called him Zurdo Robales, The Left-Handed Robber. At 13 he dominated the games; at 15 he turned professional for $83 a month in Mexico's lowest league, and at 19, by then rookie of the year in Mexico's major league and property of the Dodgers, Valenzuela learned how to throw a screwball.

Now, let's say we find a Mexican who quit school in the fifth grade because he wanted to learn only baseball. Let's give him supernatural poise, along with a diabolical screwball, a strong curve, 90 mph fast ball and control so good he can throw any pitch anywhere he wants it at any speed.

The Mexican Sandy Koufax.

As it happens, the real Sandy Koufax, the Koufax of four no-hitters, the Hall of Fame Koufax is now an unofficial Dodger pitching coach, and Sandy Koufax thinks Fernando Valenzuela is extraordinary.

"His ability is amazing," Koufax said today. "I've never seen any other pitcher with such control of four pitches -- the fast ball, curve, screwball and change."

Did he say no other pitcher?

"Who could you name?" Koufax said. "Juan Marichal might come close, but he didn't have as good a control of all four pitches. Fernando has two different curves and different speeds on everything he throws. His fast ball is in the high 80s, low 90s. It's very effective after all his offspeed stuff, and he never throws it in the middle of the plate.

"That plate is 17 inches wide, and the 15 inches in the middle belong to the hitter.

"Fernando owns the other two inches."