What is the definition of a quality start in baseball and how does it impact a pitcher's performance?

A quality start in Baseball is when a pitcher completes at least 6 innings and allows no more than 3 earned runs. This performance standard is used to evaluate a pitcher's effectiveness in a game. It impacts a pitcher's performance by indicating their ability to keep their team in the game and give them a chance to win. Pitchers who consistently achieve quality starts are considered reliable and valuable to their team.