Starters no longer pitch the innings they used too and relievers are becoming more important in MLB every year. Yes, their are a few “Ace” starters in the game that make the big bucks but they too no longer pitch deep into games like the starters did in the past.
The role of relievers has changed
Relievers are critical pieces of any baseball team that hopes to contend and play late October baseball. The use of relievers and their value to the team has evolved over the years and today’s major league game requires the pitchers in the bullpen to fulfill certain roles. You have the “closer”, you have your set-up guys that pitch important innings, you have the long guy that comes in to pitch multiple innings, and you have relievers that are used to eat innings, probably when the team is losing. Each person in that bullpen knows their role and when they will probably be called upon to pitch. In the past it was not so clear, it was not unusual for starters to pitch some relief when the game situation called for it.
Another key part of relief pitching is your manager and pitching coach and how they plan out each game to see who is available to pitch and who isn’t based on previous usage. Then of course we have the analytics that comes into play. Back in the day, the manager monitored his starter and he called on the bullpen when he felt the time was right. We can’t forget about rule changes, MLB has changed numerous rules that have had an impact on the use of relievers, roster sizes, etc.