The Weather Was Fine, and the Home Runs Were Easy
By ALAN SCHWARZ
May 14, 2006
Keeping Score
Three weeks ago, when major leaguers were bashing baseballs at paces unseen since the so-called Steroid Era, conspiracy theorists wanted the deep flies explained by a Deep Throat. They craved someone to assign some reason — the players were juiced, the ball was juiced, the strike zone was squeezed — for this most curious offensive surge.
Who knew that the man who would emerge from the shadows might not be a man at all, but Mother Nature? Through all the speculation and the wink-wink innuendo, it turns out that the hitters simply might have been hot ... literally.
April was, by almost every measure, an abnormal month for offense. Games averaged 9.9 runs on the strength of 2.3 home runs. These were the highest totals since the bloated 10.8 and 2.6 figures posted in April 2000, when, by many estimates, players' use of illegal performance-enhancing substances was at its peak, before random testing began. When Major League Baseball made the penalties for positive tests far stronger after last season, predictions followed that offense would decrease in 2006.
But it has gone up instead. A lot. Almost as much as the temperature and the heat index in the United States, which could very well have been responsible for most of it.
Sitting in the stadiums watching all those April home runs, followers apparently did not notice just how warm the air was. According to the National Climatic Data Center, this was the United States' warmest April — reaching an average of 56.5 degrees Fahrenheit — since records began being kept in 1895. That was the year after the National League's most offensive season.
They get far fewer headlines than juiced balls and/or players, but heat and humidity play a large role in offense. High temperatures and humidity make for lighter air and fly balls that tend to carry beyond fences.
As the Mets slugger Carlos Delgado put it, "I'd say 95 percent of hitters will tell you they feel better at the plate when it's warmer."
The numbers bear this out. Merging data provided by Stats LLC and Weather Source, a provider of historical and real-time weather information based in Amesbury, Mass., Mark Gibbas of Weather Source found what he called a "meaningful and possibly substantial" correlation between heat index — an amalgam of temperature, humidity and other factors — and home runs. The April 2000 surge, he found, was at least partly caused by a 56.2 heat index that ranked sixth among the 34 years studied. Hot and cool Aprils tended to correlate with high and low offense.
"The average person doesn't see this effect at all, because they expect an even chance of home runs regardless of the temperature," Gibbas said. "Most people associate humidity with heavy, sticky air, but it's lighter and the ball goes farther."
With this information, and also knowing that one short month of games can always produce anomalous statistics, it was easy to predict on May 1 that offense would decrease to more normal levels. This happened right on cue this month, with offense cooling (along with the weather) to averages of 9.3 runs and 2.0 home runs a game through Thursday — ranking almost the lowest of the past 12 years.
This is surely disappointing to the conspiracy theorists, who must be wondering how baseball switched out the juiced baseballs so fast. But it does bring a told-you-so smile to the face of Jimmie Lee Solomon, Major League Baseball's executive vice president for baseball operations, who two weeks ago felt compelled to send several boxes of balls to a testing center at the University of Massachusetts-Lowell.
Solomon, whose office conducted its annual ball tests before the season and reported no differences, said in an interview last week that he had arranged the extra round of tests less out of concern for the balls' tightness and other characteristics than to appease the masses that were speculating about the April surge. Several whispers had baseball officials using smaller or springier baseballs to keep offensive levels as high as they had been before the stronger steroid punishments. Although many of the players caught taking steroids have been pitchers, the commissioner's office went through with the tests to try to clear the issue, at least as it pertained to the balls.
"It's a big pain in the neck," said Solomon, adding that he expected test results next week. "Every year people ask, 'What's going on with the balls?' We're not smart enough to tweak the balls. It's the same ball, the same manufacturer and the same plant as in past years. We're supposed to go out and keep double-checking these guys? But the question arose, so we go and check the balls."
The quieter offense so far in May could also muffle claims that some players remain on performance-enhancing drugs, particularly undetectable substances like human growth hormone. (They may be, but perhaps this is not drastically affecting scoring.) A full month with offense back to normal could also end speculation that the strike zone has shrunk again, and that the World Baseball Classic tired out pitchers.
More mundane explanations for this year's relatively potent offense — compared with the 1970's and 1980's, for example, and even compared with some better years of the 1990's — will have to take their place. Most obviously, fences are getting closer on average, because for every large new stadium like San Diego's Petco Park, smaller ones like Philadelphia's and Cincinnati's more than make up the difference. (The Tigers and the White Sox recently brought in their fences as well.)
Most insiders understand that offensive totals derive from many influences. The vagaries of April weather, umpires' varying strike zones, hitters' legitimate weight training, closer fences and, yes, some players' evasion of steroid rules all are strings on the marionette of offense. That does not change the instinct of many outsiders and the news media, however, to seek one identifiable explanation.
"People want a definite answer and to be able to say, 'This is it,' " said Mets reliever Aaron Heilman, who graduated from Notre Dame with a degree in management information systems and reads books on mathematics and philosophy. "But there are a lot of intangibles that they can't see. Most of the time, things have to do with a lot of factors. You can't pinpoint just one."
For those who must, the best is probably April's sultry weather. In the end, all the conspiracy talk might indeed have been a lot of hot air.
E-mail: keepingscore@nytimes.com
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