The rule was drafted exactly one hundred years ago, long before the first All-Star game and decades before Jackie Robinson broke the color barrier. There were no league championship series back then, and the rule precedes the designated hitter position by more than a half century.
That DH rule of course allowed a regular hitter to bat in place of the pitcher, only in the American League. The rule that turns 100 this year also affects pitchers, only much more dramatically and in both leagues.
In 1916, baseball adopted what is now known as the five inning rule, which stipulates that a starting pitcher must complete a minimum of five innings in order to qualify for a win. “Do not give the first pitcher credit for a game won even if the score is in his favor,” the rule states,”unless he has pitched at least the first half of a game.” A reliever, on the other hand, can technically get a win without even throwing a single pitch.
The rule seemed fair at the time, since there were so few relievers. Plus, they mainly appeared in games that were too lopsided for relievers to even figure in the decision.
It began to seem somewhat absurd by the seventies, when relief pitchers became so important that the save statistic was created. Now, in the era where the bullpen is expected to log almost as many innings as the starting pitcher, the five inning rule is definitely an anachronism.
Presently one hundred years later baseball finally needs to amend that rule, since starting pitchers average just over five innings per outing. A six inning performance is so praiseworthy it is assessed as a quality start, even though in 1916 it would have been grievously unacceptable for a starter.
This antique rule is one of the main reasons twenty game winners are so rare nowadays, especially since organizations cautiously limit the pitch counts of their starters. Relievers start getting loose when the starter reaches as few as sixty pitches, no matter which inning it is.
A more judicial stipulation, one that reflects the game of baseball today, would be to decrease the number of innings for a starter to qualify for a win. Since it only takes six innings to now get a quality start, then it should require just four to qualify for a win.
This number seems to equate the percentage of innings expected back in 1916. Pitchers were expected to last at least eight innings then, meaning that a completion of five of eight earned them a win. With modern day starters expected to go six, the four inning qualifier means they must complete two thirds of their game to earn a win. The fractions still make the task more difficult for modern day pitchers to earn a win than those of a century ago, a factor which should appease the purists of past generations.
https://youtu.be/C0qBiUlsIh4