A "quality start" for a pitcher in baseball is defined as giving up no more than three runs in six or more innings of work. For frames of reference, a starter needs to complete at least five full innings (a majority out of nine) to be eligible for a win, and three runs in six innings would be a 4.50 ERA. So how did this definition come about?
I've worked with a sliding scale, where a "quality start equivalent" (QSE) which would require at least five innings of work, and the number of innings minus the number of runs cannot be less than three. That is to say, five innings and two runs would qualify, as would seven innings and four runs. Has anyone in the sport used, or proposed, a similar "equivalent?" (On this scale, the Pittsburgh Pirates, who have "only 16 quality starts in 26 games, would have 20 QSE's. Other teams would benefit from this adjustment, of course but not to the same degree.)
Another thing that puzzles me is that a quality start is "retracted" if a starter goes six innings with no more than three runs, then pitches the seventh (and possibly an eighth) and gives up a fourth run. The way I look at it is that the pitcher earned a quality start for "three in six," then functioned as a "middle reliever," for the seventh inning. Put another way, the pitcher gave his manager the option of using only one inning of "middle" relief, even though the manager didn't use this option. Or don't the scorers see it that way?