the modified baseballs that mlb denies

I'm fascinated by a couple of images recently released by a company called Universal Medical Systems. They obtained some of MLB's baseballs from the 1998 season and performed CT scans on them. Here are links to the images:

Mark McGwire's 70th homerun baseball

Several baseballs from the 1998 season

Hopefully these links will last. Anyway, what the images show is that the rubberized core of the baseball was bigger than usual, and an unexplained synthetic rubber ring was around the core. Major League Baseball officials insist that the formation of the official game baseballs has been the same for decades.

For a rubber ring inside a baseball to be a factor in an at-bat, the batter would probably have to hit a portion of the ring directly, causing extra compaction of the ball upon contact and providing additional travel force upon re-expansion. The baseball would have a slightly higher probability of traveling slightly further than a ball that lacked the rubber ring.

Baseball (object) article on Wikipedia