It's the most difficult position to play, and Bill Freehan was the dominant catcher in his league for more than a decade. How many other men can you say that of? In the last 50 years, you've got Campy, Berra, Bench, Fisk, Carter, Rodriquez, and Piazza (almost a decade).
When you're the best player in your league at a position for ten years, you should go into the Hall.