I don't remember for sure when the role of closer was fully established. Starting pitchers used to try to go 9 innings. Now we have a model where starters may throw 100 pitchers of maybe a few more before being replaced or if they get into any trouble, they are yanked early and we seem to have 7th and 8th inning setup men and a closer. A point here is the approach to handling the pitching staff is continually evolving and probably will continue to change as the years go by. Perhaps the idea of a shared closer role is not that far fetched. Sometimes the guys could fulfill the role of the setup man or the closer, whichever seemed to be needed the most at the time. Creative handling of the staff, if an innovation seemed to work, would soon be copied and pitchers would learn to adapt to the new reality. Look at the Yankees this year with 3 guys who could all have been closers.