The closer role and the New York Yankees. These two things will forever instantaneously take you to the greatest to ever do it, Mariano Rivera. However, even Mo had to hang it up, and that left a hole that would never be completely filled again. The best management could do is minimize the impact of that loss and the pressure for whoever had to step in that role would be immeasurable. They got a crash course in doing so in 2012, however, when Rivera was lost for the year with an ACL tear early in the season.