Mr. Siwoff (pronounced SEE-woff) was 99 when he died Nov. 29 at his home in New York City. His daughter, Nancy Gilston, confirmed his death but did not cite a specific cause.
In March, Mr. Siwoff sold the Elias Sports Bureau to his grandson, Joe Gilston, but for several months afterward he continued to show up for work almost every day.
Trained as an accountant, Mr. Siwoff appreciated the importance of numbers. He once turned down a job offer from the Internal Revenue Service to keep working at Elias, which was founded in 1913 to provide baseball statistics to newspapers and wire services.
After buying the business in 1952, Mr. Siwoff struggled for a few years — still delivering updated statistics to sportswriters by hand — until the Elias Sports Bureau became the NFL’s official keeper of records in 1960.
Mr. Siwoff and his staff, which he called “the toughest team in sports to make,” pored over decades of documents of old NFL games and uncovered more than 300 previously unknown records. In codifying a haphazardly kept record book, they reduced Green Bay Packer Don Hutson’s presumed record of 100 touchdown pass receptions to 99.
“We’re the custodian of the statistics, and we have a reputation for accuracy,” Mr. Siwoff told the Hartford Courant in 2004. “We’re in a fishbowl. People would like to say, ‘We gotcha.’ It’s possible something gets by us. We’re susceptible to human error, but no place corrects one faster.”
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During the 1960s, Mr. Siwoff’s company began to tabulate statistics for the NBA, the National Hockey League, television networks and, ultimately, Major League Baseball, which considers its historical records nothing less than a sacred covenant with its fans.
“The integrity of the statistics is vital,” Mr. Siwoff said in 1990. “Imagine if you couldn’t trust the numbers that came out of the stock market. If you trivialize this, after a while it magnifies — there will be hundreds and hundreds of differences.”
By the early 1970s, Elias had begun to rely on computers, which made Mr. Siwoff’s work easier — and, in some ways, infinitely more complex. His staff came to include dozens of like-minded researchers working round the clock on the 58th floor of an office building near the New York Public Library: “One font of knowledge overlooking another,” as Mr. Siwoff put it.
Elias began publishing official record books for various sports, and Mr. Siwoff sat on committees that recommended rules changes in pro football and baseball.
He and his researchers began to use statistics to examine baseball games and seasons in countless ways: how hitters fared in day games and night games, at home or on the road, against left-handed or right-handed pitching. They measured the effectiveness of hitters — and pitchers — with runners on base. They evaluated players’ tendencies to hit the ball to right field or left field and calculated the stolen base percentages of base runners and, conversely, the ability of catchers to throw out potential base stealers.
Mr. Siwoff and his teams discovered many bizarre anomalies that make baseball so endlessly fascinating to its fans. Pat Tabler, who had an otherwise modest career from 1981 to 1992, earned his nickname of “Mr. Clutch” by hitting almost .500 with the bases loaded. Pete Rose, baseball’s all-time leader in hits with 4,256, was helpless against Bob Owchinko, compiling a batting average of only .095 against the journeyman left-hander.
Mr. Siwoff had hoped teams’ front offices would want to buy the detailed trove of information that his staff assembled each year, but he had few takers at first.
“To analyze one league for one season, it took us eight books and about 40 pounds of paper for each team,” he told the Miami Herald in 1986. “What amazed me was that it was the fans, not the teams, that seemed most interested in it.”
In 1985, Mr. Siwoff began to publish the Elias Baseball Analyst, which Washington Post sports columnist Thomas Boswell pronounced “the best book of baseball statistics ever created. By a multiple of about 10. It revolutionizes baseball stats and obliterates all competition.”
Micro-level statistics began to permeate the sport from top to bottom, changing the way fans understood the game and how teams managed their lineups. Trades were made based on findings in the Elias books.
Others took up the statistical analysis of baseball, including Bill James and the Society for American Baseball Research, but, to Mr. Siwoff, numbers were only a starting point for grasping the intricacies of his favorite sport.
“Statistics can be cold and trivial,” he said in 1973. “But they can also be alive and full of drama. What I enjoy most about statistics is the chance they give you to relive the past.”
Seymour Siwoff was born Nov. 1, 1920, in Brooklyn. His father was a shoemaker, his mother a homemaker.
He began working for Elias in 1939, while studying at St. John’s University in New York. After graduating, he served in the Army during World War II and was wounded in battle in Italy.
He returned to Elias as an accountant after the war and then bought the company a few years later. Mr. Siwoff stopped publishing the annual Elias Baseball Analyst in 1993, but the firm’s record-keeping portfolio has continued to expand beyond baseball, the NFL, NBA and NHL to include the Women’s National Basketball Association and Major League Soccer, as well as sports websites, publications and television networks.
Mr. Siwoff was also a member of the Baseball Writers’ Association of America, which votes on players for the National Baseball Hall of Fame.
His wife of 70 years, the former Gertrude Schatzberg, died in 2018. Survivors include two children, Nancy Gilston of New York and Ronald Siwoff of Chester, N.J.; four grandsons; and two great-grandsons.
Mr. Siwoff grew up as a fan of the Brooklyn Dodgers and was old enough to have watched Babe Ruth and Lou Gehrig play. He never wanted to name the “best” player in baseball history, but he often said Willie Mays was “the most exciting” player he had seen.
“Joe DiMaggio got a hit in 56 straight games. That’s not a number, it’s a story,” Mr. Siwoff said in 1994. “Statistics are institutionalized romance. That’s the way I look at it. That’s why I got into this business in the first place.”
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