It's interesting that people talk about bullpen over-use, when relief pitchers used to pitch 90 or 100 innings regularly. Look at the innings totals of our own guy, Chuck Crim! https://www.baseball-reference.com/players/c/crimch01.shtml Mike Marshall, Elroy Face, Goose Gossage, etc, etc, etc, etc. These guys weren't appearing in 80, 90 games. They were pitching 2-3 innings at a time. Dan Quisenberry had a 4 year stretch in the 80's where the FEWEST IP in a season he had was 129, without starting a single game. https://www.baseball-reference.com/players/q/quiseda01.shtml What's going on now isn't necessarily revolutionary, just managers understanding and realizing that using your best reliever exclusively in the 9th inning with a 1 to 3 run lead is stupid and terrible strategy, and that you are, in fact allowed to use your relievers for more than one inning at a time.