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In baseball statistics, a quality start is awarded to a starting pitcher who completes at least six innings and permits no more than three earned runs.
The quality start was developed by sportswriter John Lowe in 1985 while writing for the Philadelphia Inquirer. The statistic is preferred by sabermetricians to that of winning percentage(the number of wins garnered by a pitcher as a fraction of his total starts) insofar as it acts independent of such factors beyond a pitcher's control such as fielding errors, blown saves, and poor run support. ESPN.com terms a loss suffered by a pitcher in a quality start as a tough loss and a win earned by a pitcher in a non-quality start a cheap win.
An early criticism of the statistic, made by Moss Klein, writing in The Sporting News, is that a pitcher could conceivably meet the minimum requirements for a quality start and record a 4.50 ERA, seen as undesirable at the time. Bill James addressed this in his 1987 Baseball Abstract, saying the hypothetical example (a pitcher going exactly 6 innings and allowing exactly 3 runs) was extremely rare amongst starts recorded as quality starts, and that he doubted any pitchers had an ERA over 3.20 in their quality starts. This was later confirmed through analysis of quality starts recorded from 1984 to 1991, which found that the ERA in quality starts during that time period was 1.91.