University professor emeritus of mathematics Ken Ross began his lecture on the statistics of baseball with a surprising admission about the spread of steroids in the game.
“I have to confess, I’m on them,” said Ross, who is well under 6 feet tall with a slight build.
“You should have seen me before,” he said with a smile.
To a crowd of 13, Ross presented a lecture on probability and the American pastime Tuesday at the University Bookstore, in order to promote the newly re-released paperback edition of his book, “A Mathematician at the Ballpark.” Wearing a Eugene Emeralds ball cap, Ross, a lifelong baseball fan, discussed the advances in stat-keeping that have improved the ability of fans to predict team and player performance. He charted the evolution of stats such as earned run average (ERA) and batting average.
On a notepad resting on an easel, he worked out the formulas that produce such standard baseball stats as slugging percentage, on-base percentage and on-base plus slugging percentage – stats found on the back of every baseball card today. By describing the various factors that go into these statistics, he was able to show how slugging percentage and on-base percentage track the actual performance and value of a player much better than the standard batting average. With insights such as these, Ross said, baseball managers can take better advantage of team strengths and favorable matchups, and fans can understand the game on a much more intimate level. More important, fans can also gain a better understanding of oddsmaking, something Ross felt he had been unable to teach in his decades of statistics and math classes.
“Through those 20 or 30 years, I avoided odds,” he said. “Because it was not the right way to (teach) probability… and it was ignored in texts.”
“I realize that if I had just started with odds… probability would have made much more sense,” he said.
Dan Schlewitz, author of the book’s new appendix for fantasy baseball enthusiasts, was also on hand to discuss the computer simulations that he performed that demonstrated the ability of different statistics to predict baseball outcomes with varying degrees of accuracy. According to Schlewitz, these simulations also showed him how much human individuality can impact an otherwise predictable event.
“It’s really important to think of context,” he said.
Ultimately, writing his book allowed Ross to indulge his two favorite pursuits at once.
As Stanford University researcher and author Keith Devlin wrote in his review of the book, “Professor Ross loves baseball and math with a passion.”
Graduate student Zack Barnett enjoyed the talk, especially seeing how variables such as injury, batting order and ballpark location can alter outcomes.
“I’m intrigued by the human element, the human connection,” he said.
Ross, retired since 2000, taught mathematics and statistics at the University for 35 years, and is former president of the Mathematical Association of America.
Baseball Stat Categories
ERA: Earned run average, the number of earned runs given up by a pitcher, divided by the number of innings pitched, multiplied by nine. ERA does not include runs given up as a result of fielding errors.
Batting average: The three-digit decimal most often associated with a baseball player, the number of hits per official at-bats. If a batter is walked or hit by a pitch, for example, the at-bat is not included.
Slugging average: The total number of bases (singles, doubles, triples, home runs) hit by a hitter, per official at-bats.
Plate appearance: Any time a batter steps up to the plate. The result can be a hit, out, walk, hit-by-pitch, bunt or anything else.
On base percentage: The number of hits, walks and hit-by-pitches per plate appearances.
On-base plus slugging (OPS): The weighted addition of slugging percentage and on-base percentage, and as far as Ken Ross is concerned, the best way to determine the true value of a player to a baseball team.