What should it take for a closer to get in the Hall of Fame?

Trevor Hoffman and Billy Wagner have solid Hall of Fame cases. But how elite should a closer be to get into Cooperstown? Trevor Hoffman's career intersected nicely with my personal baseball fanaticism. Right as I was learning who the sixth- and seventh-inning relievers were for every team -- you know, for fun -- Hoffman was becoming an All-Star closer. Of his 51 career saves against the Giants, I probably watched 30 or 40 of them, which is roughly equivalent to a full season for a closer. His mi...