CERA is mostly worthless even when used to compare catchers on the same team since so many factors change from game to game (opponent, lineup, weather conditions, etc.) CERA is completely worthless when comparing catchers that don't play for the same team. As for the list of defensive catchers above, I'd say their team's success probably had more to do with the pitching staff they were catching rather than their ability to cause a call a good game.