Sometimes, when a wood bat strikes a baseball thrown at speeds greater than 80 miles per hour, the wood bat breaks. Sometimes the bat shatters, sending pieces of bat hurling through the air at great speed. Sometimes, these whirling, spinning shards of wood strike and injure people. Sometimes very seriously.
At the time, the broadcasters didn't realize how serious Colvin's injury was. The shattered bat, in fact, punctured his chest wall, putting Colvin in the hospital for several days. (And no one has yet figured out why Kevin Youkilis was the Cubs trainer that day.)
Colvin's injury came two years after MLB began looking into the issue of shattered bats. In the final three months of the 2008 season, 2,232 bats broke, with 756 of them separating into multiple pieces. MLB responded by setting up a committee comprised of wood and engineering experts to study the issue.
What did they learn?
The problem, in large measure, came from the increased use of bats made from maple, supplanting ash bats, which had been the standard in Major League Baseball for 50 years. Ash had replaced hickory as the wood of choice for bats when players opted for a lighter wood, in order to increase their bat speed.
So, after fifty years of success with ash bats, why did players switch to maple?
Maple is stronger than ash, and thus better for hitting the ball long distances. Even so, most players stayed with ash until after the 2001 season. That year, Barry Bonds hit 73 home runs using maple bats, breaking the single-season home-run record. A performance-enhancing bat, if you will. Today, more than half of all major leaguers use maple bats.
The problem is that maple bats break far more often and in more dangerous ways than ash bats. Maple bats "account[ed] 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," according to David E. Kretschmann, a research engineer with the federal government's Forest Products Laboratory at the University of Wisconsin at Madison, and a member of MLB's bat study committee.
A report in the Chronicle of Higher Education explains why maple bats shatter more frequently and in different ways, compared to ash bats:
One [explanation] 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, [according to Lloyd V. Smith, an associate professor of mechanical and materials engineering at Washington State University].
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.
Even with this information, and the potential for more Colvin-type injuries -- or worse -- MLB hasn't banned maple bats. Many players prefer them, despite the risks to themselves and others. And MLB can't simply change equipment rules without the acquiescence of the Players Association.
Instead, before the 2010 season, MLB required changes in bat dimensions at the major-league level and banned the use of certain types of maple bats in the minor leagues. For major leaguers, maple bats are now inspected and must meet new specifications: the maximum diameter of the barrel can be no larger than 2.61 inches (down from 2.75 inches, previously) and the minimum size of bat handles was increased about 1/50th of an inch. In addition, the league "now requires that bat makers place ink dots on the handle of their maple bats to better identify the straightness of the grain. If the grain is straight, the ink will bleed in the wood from the handle to the barrel, which is preferable." In the minors, restrictions were placed on the density of sugar maple used to manufacture bats and the use of silver and red maple in bats was banned.
The new Collective Bargaining Agreement between the players and owners carried over the minor-league density restrictions, but only for those players who have never had an at-bat in the majors. Any player who's had a major-league at-bat can continue to use the low-density maple bats, for the entirety of their careers.
With the changes made to date, the number of broken bats has declined since the 2008 season. But the problem has not been eliminated. Which means a high risk of more incidents like the one involving Tyler Colvin.
Jason Rosenberg (@Jason_IIATMS), the founder and editor of the Yankees blog It's About the Money, Stupid, has been covering the maple-bat issue for years. You can and should read all of Jason's research and analysis here. I relied on much of Jason's work in preparing this story.
I asked Jason for his view of the new rules on bat density for new players, and about other possible solutions to the problem of shattering maple bats. Here's some of what he had to say:
I’ve been as outspoken as anyone about this issue. The new restriction on bat density for new players is a step in the right direction, but it is not enough.
A number of potential solutions have been developed. Some include radical multi-piece bats that will likely never see a major league game under current MLB Rule 1.10, as they fundamentally change the time-honored equipment of the game. Other solutions include ultra-thin polymer films that wrap the bat to keep the barrel and handle in place should the bat suffer what the manufacturers call a "multi-part failure." The polymer has been tested with positive results at MLB's testing facility in Lowell, Massachusetts.
Regardless of the possible remedies now or in the future, as long as the players want the thin handle, heavy barrel bats that create a whip-like action, bats will continue to shatter. According to MLB regulations, the difference between the bat length and weight can be no greater than 3.5. In other words, a 35" bat cannot be lighter than 31.5 oz. Bigger barrels, narrower handles and bats that push the limits of this rule (or exceed them due to player modification (sanding the handles for weight/narrowness) all greatly contribute to this problem.
Small steps forward for MLB, even when bigger, potentially better solutions are available. But this issue, especially, is on the players, who continue to look for any possible advantage to improve their performance in the batter's box.
Fingers crossed that nothing like the Tyler Colvin incident -- or worse -- ever happens again.