“During our examination of the bat, we noticed a circular area .75 inches wide in the center of the top barrel. The finish in the area has also been touched up to mask the circular area. Alterations of this nature indicate the barrel has been drilled and filled with cork….we had the barrel x-rayed and (it) confirms that the barrel has been drilled and filled with cork."
According to the MythBusters August 8, 2007 baseball special, the ball hit by a corked bat travels at only half the speed of a ball hit by an unmodified bat, causing it to go a shorter distance. The cork inside the bat actually absorbs the kinetic energy like a sponge, hindering the batter's performance. In addition, because corked bats are lighter, they have less momentum to transfer to the ball, bringing them to the conclusion that the use of a corked bat had fewer benefits over a regular bat. The show also notes that while filling a bat with cork makes it lighter, there is nothing in the rule book that prevents a player from simply using a lighter, uncorked bat. However, contrary to the last note in the episode, the reason players "cork" a bat is to keep it as long as a heavier bat, but make it lighter; which cannot be done without some kind of non-wood filler in the sweet spot of the bat.