Why home runs are way down at CWS
June, 27, 2011
6/27/11
11:46
AM ET
By Greg Rybarczyk | ESPN.com
Home runs are down at the 2011 College World Series -- way down. Headed into the start of the finals on Monday in Omaha, Neb., only seven home runs have been hit in 12 games, compared to 32 in 14 games in 2010.
This dramatic power outage coincides with the cross-town move from Rosenblatt Stadium to TD Ameritrade Park. The dimensions of the two parks are virtually the same, and the change of venue has nothing to do with the drop in home runs. Nor is it due to an isolated cluster of unusually strong pitching performances.
The difference is in the bats.
On Jan. 1, the NCAA implemented a long-anticipated new standard for regulating the performance of bats. The NCAA originally sent a memorandum to bat manufacturers on Sept. 16, 2008, explaining the intention to achieve “wood-like performance in non-wood bats.” The details of how the NCAA bat standards changed are rather involved, but the net effect is quite simple: The bats are less “bouncy,” and balls come off the bats slower.
According to Dr. Alan Nathan, a baseball physicist who also serves as a member of the NCAA Baseball Research Panel, the NCAA changed the way it measures bats in order to provide a more consistent performance limit (for a detailed explanation of the old and new measurement methods, read Dr. Nathan's article). The limit for non-wood bats was set at a level that is just barely “bouncier” than the bounciest wood bats available.
Nathan’s research has indicated that restricting bats via the new standard lowers the batted ball speed by about 6 mph for a typical fly ball of 380-400 feet.
Analyzing an aerodynamic model for batted balls (Hit Tracker), a reduction of 6 mph in batted ball speed corresponds to a 30-foot reduction in distance. Home run data from MLB over the last five and one-half seasons suggests that this would reduce home runs by roughly 50 percent. Data from all Division I games in 2010 and 2011 fit well with this analytical estimate: Home runs have dropped from 0.94 per team per game in 2010 to 0.52 in 2011, a 42 percent reduction.
What will be the long-term impact of the bat standard changes? Scouts and analysts will have to adjust their methods of assessing college players to factor in the dramatic discontinuity in college baseball stats and performance from 2010 to 2011. The lower power and run-scoring environment may favor players specializing in speed or defense in the short term. However, some college home run fences may need to come in to rebalance the game, as the rough equilibrium between the existing fences and the superseded bats has been disturbed.
Runs per game dropped an unprecedented 20 percent this season. Nevertheless, the harmonization of the performance of college and professional bats has removed a major difference between the two games.
This dramatic power outage coincides with the cross-town move from Rosenblatt Stadium to TD Ameritrade Park. The dimensions of the two parks are virtually the same, and the change of venue has nothing to do with the drop in home runs. Nor is it due to an isolated cluster of unusually strong pitching performances.
The difference is in the bats.
On Jan. 1, the NCAA implemented a long-anticipated new standard for regulating the performance of bats. The NCAA originally sent a memorandum to bat manufacturers on Sept. 16, 2008, explaining the intention to achieve “wood-like performance in non-wood bats.” The details of how the NCAA bat standards changed are rather involved, but the net effect is quite simple: The bats are less “bouncy,” and balls come off the bats slower.
According to Dr. Alan Nathan, a baseball physicist who also serves as a member of the NCAA Baseball Research Panel, the NCAA changed the way it measures bats in order to provide a more consistent performance limit (for a detailed explanation of the old and new measurement methods, read Dr. Nathan's article). The limit for non-wood bats was set at a level that is just barely “bouncier” than the bounciest wood bats available.
Nathan’s research has indicated that restricting bats via the new standard lowers the batted ball speed by about 6 mph for a typical fly ball of 380-400 feet.
Analyzing an aerodynamic model for batted balls (Hit Tracker), a reduction of 6 mph in batted ball speed corresponds to a 30-foot reduction in distance. Home run data from MLB over the last five and one-half seasons suggests that this would reduce home runs by roughly 50 percent. Data from all Division I games in 2010 and 2011 fit well with this analytical estimate: Home runs have dropped from 0.94 per team per game in 2010 to 0.52 in 2011, a 42 percent reduction.
What will be the long-term impact of the bat standard changes? Scouts and analysts will have to adjust their methods of assessing college players to factor in the dramatic discontinuity in college baseball stats and performance from 2010 to 2011. The lower power and run-scoring environment may favor players specializing in speed or defense in the short term. However, some college home run fences may need to come in to rebalance the game, as the rough equilibrium between the existing fences and the superseded bats has been disturbed.
Runs per game dropped an unprecedented 20 percent this season. Nevertheless, the harmonization of the performance of college and professional bats has removed a major difference between the two games.
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