http://www.nytimes.com/2007/02/25/sp...l/25score.html

By ALAN SCHWARZ

Published: February 25, 2007

As newfangled baseball statistics go, on-base plus slugging percentage, or O.P.S., has become mainstream. Stadium scoreboards display it right alongside batting average. It has even appeared on the backs of Topps baseball cards.

What is O.P.S.’s reward for its widespread acceptance? For its simple approach of adding two official categories? Naturally, to have the statistics cognoscenti deem it inadequate.

This is not necessarily unreasonable. While O.P.S. may be the Harley to batting average’s Schwinn, merely summing on-base and slugging percentages is a vestige of the statistic’s birth in the early 1970s, when multiplication and square roots had yet to be invented (or, more accurately, were not available via Excel spreadsheets). Since they were first married, like any royal couple, on-base and slugging percentages have been known to be anything but equal, with their relationship being the subject of rampant debate.

“There’s a lot of ranging opinion over how much more valuable on-base percentage is,” said Victor Wang, a high school junior from Bloomington, Minn. “The book ‘Moneyball’ said it was three times. It goes down all the way to 1.5. But a 1-to-1 ratio? I knew that wasn’t right.”

Only 16 and dreaming of a career in baseball number-crunching, Wang was so moved to investigate this issue that he examined the statistics for every team since 1960 — via Excel, of course — to see which weights applied to on-base and slugging percentages most closely correlated with each team’s runs. He discovered that weighting on-base percentage 80 percent more than slugging percentage worked best, and he published a short article about it in “By the Numbers,” a Society of American Baseball Research journal.

Most stat-savvy baseball folks sense that on-base percentage is more valuable, perhaps drastically so, because it better recognizes the importance of not making outs. David Wright of the Mets agreed last week, saying: “You can always make things happen when you get on base. When I think of slugging percentage, I think of sitting back for the three-run homer, which might not happen.”

Wang wasn’t the first researcher to look into exactly how much more valuable on-base percentage may be. The Hardball Times, a statistics-oriented think tank out of the Baseball Prospectus mold, recently identified the same factor of 1.8 and started weighting O.P.S. accordingly. Better yet, one last simple step — dividing by four — put this new measure (called Gross Production Average) on the comfortably familiar scale of batting average, with figures generally ranging from .200 (horrible) to .265 (roughly average) to around .360 (superior). It’s a language that most fans speak.

Applied to individual players, Travis Hafner of the Indians led the major leagues last year with a .362 G.P.A., a sliver ahead of Albert Pujols of the Cardinals. Just like batting average, 10 hitters wound up .325 or higher. But they truly represented the sport’s most well-rounded batters, having weeded out walk-averse nonsluggers like the Pirates’ Freddy Sanchez, who had a .288 G.P.A. despite winning the National League batting title at .344.

Although it seems a product of the computer age, weighting statistics differently dates to baseball’s primordial days. As early as the 1860s, numbers men figured a type of weighted slugging average, only to have it hooted out of existence by singles-loving traditionalists. In 1916, the writer F. C. Lane gleefully mocked those averse to simple numerical weights — he said that when asked how much change one was carrying, nobody would reply, “eight coins” — and painstakingly derived relative values of singles, triples, walks and the like to rate players more precisely. His zeal, however, preceded that of any wider audience by several generations.

O.P.S. appeared on the scene in the 1970s, with on-base and slugging percentages being added rather than multiplied (which everyone agreed was more accurate) solely because it was simpler. O.P.S. is old enough that The New York Times published weekly top 10 leaders as early as 1985. But again, that didn’t last long. Even today, with O.P.S. the most accepted nontraditional statistic, fans still have trouble intuitively sensing if an .850 O.P.S. is good or bad.

The salvation for Gross Production Average could be how it translates a better O.P.S. into the customary .200-to-.360 scale. G.P.A.’s .300 hitters are just about as elite as traditional ones: Last year, 38 batters hit .300 in batting average, while 32 hit .300 in G.P.A. They are just not the same hitters, which is the entire point.

Having completed his investigation into the dance between on-base and slugging percentages, Wang is concerning himself with a different kind of G.P.A. these days. He had an American history test to take notes for, particularly on the Red Scare. But he said that when he was done studying, he would turn his attention back to baseball problems even older than those Bolsheviks.

“I love this stuff,” Wang said. “Even if it’s a meaningless problem. Meaningless to some people, I mean.”GPA

Gross Production Average, a variation of OPS, but more accurate and easier to interpret. The exact formula is (OBP*1.8+SLG)/4, adjusted for ballpark factor. The scale of GPA is similar to BA: .200 is lousy, .265 is around average and .300 is a star.