In Game 5 of the 2015 World Series, with the Kansas City Royals leading the series 3-1 against the New York Mets, reliever Wade Davis came out of the bullpen, pitched a shutout inning and helped end the Royals’ 30-year World Series drought. In so doing, he started the current era of MLB postseason bullpen fever. The Royals were patient zero for this fever — building a power pen and winning it all in 2015 — and then the fever spread.