Economist Paul Sommers delves behind the numbers to help tell the story of baseball.
By Matt Jennings
Paul Sommers is not Bill James. He wants you to know that right off the bat.
It’s not that Sommers doesn’t admire the work of the noted baseball editor and statistician who revolutionized the use of scientific data to interpret the value of baseball players and teams. It’s just that James is a “seamhead,” a baseball fanatic, and Sommers, well, he may be a fan in the conventional sense, but that’s as far as he’ll go.
“I know very little about the history of the game,” the economics professor says
matter-of-factly on a warm summer morning in his cozy Munroe Hall office. “Aside from the obvious benchmarks, I don’t know a lot of institutional facts. I’ve never played in a Rotisserie league, and I wasn’t the type of kid who spent hours poring over box scores in the morning paper.”
Yet during the past 25 years, the economist has penned more than 60 mathematical journal articles that address the wide world of sports. Basketball, hockey, football, and the Olympics have all been examined under his economic microscope, but it is baseball that has received the greatest attention. Starting with “Pay and Performance in Major League Baseball: The Case of the First Family of Free Agents,” which he wrote with Noel Quinton ’79 for the summer 1982 issue of the Journal of Human Resources , Sommers has authored more than 30 articles about “America’s Pastime.” Using statistical models to compute probabilities and support arguments, he has hypothesized that high free-agent salaries do correspond with increased team revenue; that Ted Williams probably was the greatest hitter who ever lived; and that Babe Ruth would have hit close to 900 career home runs if he hadn’t spent the first five years of his career as a pitcher.
“There’s a lot I don’t like about economics,” Sommers says, as a way of explaining his interest in the sports arena. “There’s just too much eco-babble out there, abstract thought. I really enjoy applied work”—his Ph.D. dissertation examined the issue of birth control—“and baseball, with its hard and fast measures of productivity, is a natural subject of study.” That, and the fact that many of Sommers’s students gravitate toward sports. In his course on statistics, Sommers requires a group paper in which students apply econometric techniques to topics of their choice; baseball pops up quite often. Sommers says that when surprising results arise, he’ll then work with the student to adapt the paper into a publishable research note. To this end, Sommers has collaborated with more than 100 student coauthors on nearly half of his journal articles.
During the past several years, Sommers’s research has reflected the mood of the baseball fan, from wonder at the record-setting home-run performances by the likes of Sammy Sosa and Mark McGwire at the turn of the 21st century (“Chasing Hank Aaron’s Home Run Record,” The College Mathematics Journal ) to cynicism in the wake of alleged steroid use by the same power hitters (“Chemical Bonds,” Journal of Recreational Mathematics ).
In fact, from a cultural and historical standpoint, Sommers’s research—examined broadly and with 20/20 hindsight—proves to be prescient, even in cases where the numbers didn’t add up as predicted. For example, in “Chasing Hank Aaron’s Home Run Record,” written after the 2000 season, Sommers and his undergrad cohorts Peter Harwood ’99, Steve Bisgaier ’03, and Ben Bradley ’03 used what Sommers calls a simple econometric formula to predict that Mark McGwire and Ken Griffey Jr. would break Hank Aaron’s career total of 756 home runs. By taking each player’s average number of home runs per year, the standard deviation from the average, and the players’ respective ages, Sommers projected a 79 percent chance that McGwire would hit number 756 by the age of 42. (Since Aaron retired at 42, Sommers based his prediction on each player reaching the milestone by the same age.) Griffey, according to the model, was a near lock, with a 99 percent probability of passing Aaron’s mark by his 42nd birthday. (At the time, McGwire was 37 years old and had hit 554 homers; Griffey was 31, with 438 home runs.)
McGwire retired the following season under a cloud of suspected performance- enhancing-drug use. In his last year as a pro, he hit just 29 home runs, well below his average of 46 home runs a year and a far cry from the 70 he had hit just three seasons earlier. Since 2000, a series of injuries had prevented Griffey from playing a full season, and he is now considered a long shot to even reach 700 home runs.
So while the projections were off—clearly there weren’t variables for injuries and suspected drug use—the paper itself accurately reflects the times, when the idea of drug-induced performance enhancement was far from people’s minds. Even more telling, says Sommers, is who the paper didn’t include.
“Barry Bonds wasn’t even on the radar screen [then],” Sommers says, chuckling softly. “But that changed.” The very next year, Bonds smacked 73 homers, snatching the season record from McGwire and catapulting himself into the home-run spotlight. So, Sommers conducted the exact same experiment (“a technical pun,” he explains), substituting Bonds for McGwire. At the time, Sommers determined that there was better than a 50-50 chance that Bonds would pass Aaron by the time he turned 42. As it turns out, this may have been an underestimation. Up through the 2002 season, Bonds had averaged 36 home runs a year. Since then, his power numbers have actually increased, a historic anomaly. Among Ruth, Bonds, Mays, and Aaron, only Bonds has increased his number of home runs per year after his 35th birthday (the subject of Sommers’s 2005 paper “Chemical Bonds” in the Journal of Recreational Mathematics).
On this subject, a pained expression creases Sommers’s face. Though injuries and perhaps stress have started to take their toll on Bonds—currently number two on the all-time list, trailing Aaron by about 40 home runs—Sommers is convinced he will pass Aaron, if not this season, then next. The economist doesn’t need any statistical model to tell him this, just his gut. And this saddens him.
For all the protestations that he’s not a baseball junkie, he admits that as a child growing up in Yonkers, he would take a transistor radio to bed with him and listen to Brooklyn Dodgers games under the covers. And if you prod him just enough, he’ll talk about moving to California and playing shortstop for the Elks, a Little League club in Santa Monica (“I was a good fielder,” he allows,” but a miserable hitter”). So while he may not be Bill James, he is a fan in the conventional sense. “And if Bonds does in fact break the record,” he says, “this fan”—and here he points to himself, and to his heart—“will not be impressed.”