Are Today’s Home Run Hitters Just Carpetbaggers—A Synthetic Discovery

The May 2001 edition of Discover magazine has a fascinating article by Curtis Rist in it that just might explain why so many home runs have been hit in the past eight years.

The article, entitled "Foul Ball?," will take a bit of the steam out of conspiracy theorists, who believe that the owners have covered up a juicing of the baseball in order to jack up offense. (One of the leading proponents of this theory, Eric Walker, whose fascinating albeit occasionally over-florid volume The Sinister First Baseman is something of an unknown classic in hyperliterate sabermetric circles, calls this phenonmenon the "Silly Ball").

Rist's article puts a completely different spin on the "silliness" inherent in the recent home run explosion. It turns out that the changing contents of carpet fibers may be a significant factor all this.

Oddly, criminologist Dennis Hilliard, director of the crime lab at the University of Rhode Island, is the key man in this discovery. With admirable forensic zeal, Hilliard and his team of analysts compared the components of baseballs from six different years (1963, 1970, 1989, 1995 and 2000) to determine the differences in them.

The result was that the synthetic fiber content of the 2000 baseball was close to 22%, which is significantly higher than the major league guideline (15% plus or minus 3%).

What's the difference in having more synthetic materials used as part of the baseball's inner windings? As Hilliard's colleague Linda Welters explains in the article, it's all about the susceptibility of the ball to moisture.

Wool absorbs moisture (we're talking about moisture from the air) quite readily, and humidity can tend to deaden a ball by relaxing the tension and reducing fiber elasticity. Polyester, on the other hand, cannot absorb water.

Where does the carpet fiber come into this? It has to do with the components used in the yarn wound into major league baseballs. The Paul Dubin Company of Centerville, Massachusetts has been producing this yarn for Major League Baseball since 1976; the fibers used to create this yarn is recovered waste from carpet manufacturers.

Welters surmises that the decline in all-wool carpets has caused the rise in the percentage of synthetic fibers in the yarn.

And the rise in the percentage of fibers in the yarn may account for a good portion of the increase in homers per game over the past decade (1.58 in 1990; 2.34 in 2000).

Paul Dubin, in a statement that will leave conspiracy theorists with something to believe in, denies the accuracy of the crime lab's findings. If such is actually the case, however, it's clear that the change in the baseball was essentially unintentional.

Of course, there are other factors that could still account for some of the surge in homers. (We've discussed some of those recently, and reader Scott Robinson wrote a paper for his college English class on this topic partially as a result of our discussion here. By the way, Scott, how did you do on that paper? If my recollection is correct, Scott concluded that the baseball was the primary culprit in the home run explosion.) Separating these out in a way that quanitifies each is impossible, of course—but it would be ironic to think that much of the change we've seen could be due to a change in something we can't see.

A final note: scoring is down in the big leagues so far this year (about 11%), but home runs are down only marginally (through May 11th, 2.31 homers were being hit per game). I'll leave it to you number-crunchers out there to come up with estimates as to how much more offense could be lopped off as a result of returning the synthetic content of the baseball to its proper specifications, but it's clear that there's still some more room for shrinkage.

Thanks to my father, Donald Malcolm, Sr., for bringing the preceding material to my attention.