This year's World Series has certainly showed baseball fans a few things. Discarded veteran players sometimes outperform highly paid all-stars. Dominant pitching performances can be ruined by an inexperienced bullpen. Thick black beards are somehow in vogue.
And it showed that despite two straight years of laboratory tests—conducted at leading research universities—and subsequent rules changes, Major League Baseball hasn't fixed the troubling problem of bats shattering into shards of wood that fly into players and fans.
As with most of the several hundred cases each year of shattered bats, nobody was hurt during the handful of bat-breaking incidents in the championship series between the San Francisco Giants and the Texas Rangers.
But the danger remains real. In one of the last games of the regular season, on September 19 in Miami, Tyler Colvin of the Chicago Cubs was running home from third base when the end of the bat wielded by his teammate Welington Castillo sheared off and flew into his chest. The jagged chunk of wood struck just below Mr. Colvin's collarbone, puncturing his chest near a lung and leaving him hospitalized for several days. A few weeks earlier, a broken bat tore a six-inch gash across the right shoulder of Brad Ziegler of the Oakland Athletics.
It's a problem for which Major League Baseball, like many businesses needing expert advice, sought help from specialists at the nation's research universities. Rules changes based on that advice have led to a reduction in bat-breaking incidents of more than 40 percent over the last two years.
"Bringing science to this issue helped us enormously in understanding it," says Daniel R. Halem, Major League Baseball's senior vice president for labor relations.
And yet the injuries this year to Mr. Colvin, Mr. Ziegler, and others show the problem isn't solved. The professorial backing helped Major League Baseball persuade players to accept the new rules, which govern a series of largely technical characteristics of bats, such as the density of the wood and the slope of the grain.
Still needing more attention, though, according to some university experts, are more cherished player choices over the acceptable types of wood and dangerously thin bat handles. As a result, the breaking-bat problem has only been "minimized" in the past two years, says Lloyd V. Smith, an associate professor of mechanical and materials engineering at Washington State University at Pullman. "It's not solved."
A 'Dream Team' Assembles
The issue became a major concern in the last three months of the 2008 season, when a total of 2,232 bats broke during Major League games, with 756 of them separating into multiple pieces. Major League Baseball responded that winter by forming an internal advisory committee supported by a "dream team" of university-based experts, Mr. Halem says.
The experts included James A. Sherwood, a professor of mechanical engineering at the University of Massachusetts at Lowell; Carl N. Morris, a professor of statistics at Harvard University; and David E. Kretschmann, a research engineer with the federal government's Forest Products Laboratory at the University of Wisconsin at Madison.
The committee's first set of rules changes, following the 2008 season, included a limit on the angle of the wood grain relative to the length of the bat, as the scientists concluded that straighter lines made tougher bats. The number of breaking-bat incidents promptly declined by 30 percent in the 2009 season. And, after another off-season rule change governing the density of bats, the number of incidents fell by another 15 percent this past year, Major League Baseball reported.
But one of the main unresolved issues involves the decision by many players in recent years—now roughly half of Major League hitters—to begin using bats made of maple. Players switched from ash, the favored wood for the previous half-century, after the San Francisco outfielder Barry Bonds used maple in 2001 to whack a single-season record of 73 home runs.
"For some reason, nobody said, 'No, actually, it wasn't the bat that was juiced, it was Barry,'" Mr. Smith, a baseball-testing expert who is not part of the advisory committee, says in reference to accusations of steroid use by Mr. Bonds. And those maple bats, it turns out, break far more often, accounting for 7.5 times as many multipiece breakages than did ash bats in the 2008 season, and five times as many in 2009 and 2010, Mr. Kretschmann says.
The problem represented by those numbers could soon grow even worse, given that ash trees in the United States are threatened by the emerald ash borer, a green beetle native to Asia. "We know it's going to reduce the supply of ash," says Scott Drake, a vice president of Timberco, a Wisconsin wood-products testing company that Major League Baseball uses to certify manufacturer compliance with its bat regulations. "We just don't know how soon."
Ash vs. Maple
University researchers and bat manufacturers alike can list several explanations for the difference in performance of the two woods. One involves the rings that accumulate with each year of a tree's growth. When cut into lumber, those rings become the familiar lines that run the length of a baseball bat. The tree rings emerge from each year's formation of pores that supply the tree with water and nutrients. Ash is considered "ring porous," because its pores develop in the early stage of the annual growing season, making its lines more distinct.
Maple, by contrast, is a "diffuse porous" species, with its pores more evenly distributed throughout its annual ring. The result is that when an ash bat breaks from hitting a baseball, the wood is more likely to just flake off along those lines, Mr. Smith says. The maple, however, is more likely to just disintegrate under a sufficient amount of stress, he says.
Another reason for the differing performance is that the grain lines in ash tend to run straighter, whereas the lines in maple tend to meander. That makes maple a more aesthetically beautiful wood, with "a lot of interesting textures," says Mr. Smith, whose Sports Science Laboratory performs the official bat testing for the NCAA. But that meandering is far more likely to leave the wood with a random spot of relative weakness, and thus a higher likelihood of a sudden breaking of the bat on impact. "The challenge in getting maple with straight grain is more difficult than with ash," he says.
An additional problem stems from the higher moisture content of maple. That property leads some bat manufacturers to kiln-dry maple longer than ash. The extra drying is done to reduce the bat's weight, but it also makes the bat more brittle, Mr. Smith says.
One possible solution could be an outright ban on maple bats. That might be feasible given that Major League Baseball, along with some bat manufacturers, disputes the notion that maple bats hit balls better than ash bats do.
"All we know is what we're told by our experts," says Mr. Halem, whose experts committee is still evaluating more restrictions, "and the studies we've seen show no difference in performance." Mr. Smith, whose lab has the equipment to test such things, agrees. "There is really no advantage in switching wood species," he says.
But it's not so simple. Many players are creatures of habit, and many bat makers encourage them. Seth M. Cramer, general manager of the Phoenix Bat Company, which made the maple bat that injured Mr. Colvin, says it's a simple fact that maple is a harder wood than ash. And a harder wood, Mr. Cramer says, will hit a ball farther. "I just go back to basic physics that you learned in high school," he says.