MLB: Is the 6-man rotation a trend or a phase?

On using a 6-man starting pitching rotation.

In 2021, for the first time ever, there were more starts on exactly five days of rest (37%) than four (33%).
In 2023, it happened again. (41% to 33%)
In 2024, it happened again. (42% to 32%)

Why? There’s no shortage of theories. Maybe more rest keeps pitchers healthier; maybe more rest makes them more effective; maybe having more starters takes stress off the bullpen; maybe you have enough starters that you’d rather not throw any out of the bullpen; maybe some “starts” are in reality just “bullpen games,” and so forth. These are all compelling theories, albeit none really proven out.

Maybe it’s all of those, to some extent. But we’d also argue another theory, too: It’s connected in some part to how much baseball needs to be played in a season, and how much time passes between those seasons. Don't forget that for the first 60 years of the 20th century, teams played 154 games and then went directly to the World Series, on eight different occasions starting the Fall Classic before September even ended.

For example: When Willie Mays’ 1954 Giants won the ring with a World Series sweep, they played a total of 158 games, combining regular season and postseason. The last game was on Oct. 2, giving them 193 days off before the next year’s April 13 opener.

The 2024 champion Dodgers, however, had to play 178 games, with a month of expanded playoffs atop a 162-game regular season, and they’ll get only 139 days off before starting this season against the Cubs in Tokyo (or 148 days before domestic Opening Day on March 27, for a fairer comparison).

******they keep extending the playoffs and these guys get injuries or just burned out. But I guess the owners need to make more money.

https://www.mlb.com/news/why-more-mlb-teams-are-using-6-man-rotations?partnerId=it-20250113-12284310-mlb-1-B&utm_id=it-20250113-12284310-mlb-1-B&lctg=95464253