ESPN scrapped the dead-center cam after slightly more than a year. (Fox has used the dead-center shot on national broadcasts of Cardinals games this season, but its Red Sox broadcasts—and those for every other team—have used the offset angle. TBS, the sport's other national broadcaster, has never used a dead-center camera.) Matt Sandulli, who produces baseball telecasts for ESPN, says that despite the extra cost and extra effort, the network probably would've kept the camera "if there was a way to get the angle uniform" in every major league ballpark. As of right now, that's not possible. In Oakland, Calif., a wall of luxury boxes precludes placing a dead-center camera. The Crown Vision center field scoreboard provides a similar obstruction in Kansas City. In Denver, the "Rock Pile" bleacher seats make installing a dead-center camera a "seat-kill," in producer parlance. Other stadiums have advertising signage where a camera would be placed.
Source : http://www.slate.com/articles/sports/sports_nut/2009/06/you_call_that_a_strike.html