SEYMOUR SIWOFF sounded somewhat bewildered by what he has wrought. He was speaking by telephone from his offices at the Elias Sports Bureau in Manhattan. The subject was Elias's latest book, "The 1988 Elias Baseball Analyst," just released by Collier Publishing to a nation of eager and hungry baseball-aholics.

The '88 edition is the fourth year for the Analyst, and it's bigger and better than ever, acclaimed by just about everyone in the business . . . and Seymour just shakes his head."It was just me fooling around with a computer back in 1962," he said. "Who'd have thought?"

Baseball, of course, has always been the sport of statistics. Numbers are everything, from win-loss records to batting averages to home run totals, etc.

In hindsight, it's no surprise that when Siwoff a baseball nut by birthright, he was born in New York and his computer got better acquainted they would A) Establish the Elias Bureau, which compiles statistics for a number of sports bodies, including Major League Baseball, the NFL and the NBA, and B) Publish their best baseball stuff in annual "Analysts" that true baseball zealots can't wait to lay out $12.95 to get their hands on.

The project has become bigger than any one man, or computer.

"The total data base is staggering," says Siwoff. "It's a company effort. I marvel that we could do this."

Everything but pizza toppings

What Elias does is take baseball stats to the next level, and then the level after that.

Take, for instance, the basic statistic of batting average. Elias doesn't just divide hits into at-bats and let it go at that. It computes batting average according to situations when the bases are empty, when runners are on base, when your team is behind in the score, when your team is ahead in the score, when you're playing on artificial grass, when you're playing on natural grass. It stops short of computing batting average according to what toppings a player had on his pizza the night before. But only just.

The Elias "Analyst" is the supreme numbers racket and baseball junkie's handbook.

It also provides a unique opportunity for the average fan to become a sort of pseudo-horsehide genius.

For instance, you're sitting around some Saturday watching the Yankees play the Orioles on TV and you throw out this aside: "Of the 74 big league managers in history who have worked at least a thousand games, Billy Martin is the best there's ever been."

This is bound to get some response, even some argument, and then you can refer to page 74 of the '88 Analyst, where the Elias people have shown that Martin's effectiveness over the years translates into almost eight extra wins a season for the club lucky enough to have him in their employ.

But do this one soon, before Martin loses another job.

Personalized attention

Other quick references:

During an Oakland game, mention that the A's steal third base more often, and with more success, than any team in the majors . . . do this when an A's player is on second base.

During an Astros game, when Nolan Ryan is pitching, bring out the chart from page 132 that shows Ryan's 11.48 strikeouts-per-nine-innings last season is the best in the history of baseball.

During a Mariners game, point out that no matter where Dick Williams has managed, his teams have always improved dramatically in his third season . . . which is what he's working this season in Seattle.

The "Analyst" also allows for more personalized attention.

When a local star like Bruce Hurst is pitching for the Red Sox and Baltimore's Eddie Murray is at the plate, you can say, "Good situation here for Hurst. Murray is 3-for-34, or .088, against him lifetime."

Or if the Giants' Kelly Downs finds himself in a bases-loaded situation you can say, "This has happened to Downs 12 previous times in his career, and the opposition has only gotten a hit one time."

It sure isn't going to bother Siwoff and the guys if you say any of the above. They're not even terribly particular that you give them credit. Just buy their book.

"There are so many things you can look at, so many variables," says Siwoff. "We just try to offer as many as we can."

Translated, that's 436 pages of everything from George Bell's lifetime stats against every pitcher he's ever faced to the little-known but true fact that whenever the Padres return from a road trip to the comforts of San Diego they win the opening game of the homestand nearly 80 percent of the time.

You don't believe it?

You can look it up.