In 1925, the use of five-man rotations surpassed the four-man method for the first time. It took longer than that for them to fully catch on, though, and it’d be disingenuous to suggest it’s been almost a century since the blueprint for starter usage was tinkered with—it’s a particular kind of baseball science, with change coming in waves.
Many teams reverted to using four starters by the 1950s, at which point lights had been installed at every stadium (except for Wrigley Field), allowing doubleheaders to be largely cut from the schedule and thus giving teams more time to rest their best arms. Gil Hodges’s ’69 World Series–winning Mets are often credited with popularizing the five-man cycle—or at least giving each pitcher four days’ rest. The Dodgers of the early ’70s are also regarded as early five-man pioneers: They had reason to be after witnessing Sandy Koufax’s premature injury-forced retirement in ’66 following mostly throwing on three days’ rest (and occasionally two when the situation called for it, as it did in Game 7 of the ’65 World Series). The vast majority of teams followed suit by the ’80s.
Regardless of the exact timing, it’s fair to say that employing five starting pitchers has long been the norm in the majors. Could the next evolution in a sport be expanding that number to six? A few teams have made a strong argument for it this season.
