What are QABs in baseball?

Quality At-Bat (QAB) - An at bat in which the batter is productive in a way that fits the situation, whether that involves advancing the runner with a sacrifice bunt or even a ground ball out, getting on base, or making the pitcher throw a lot of pitches. Thus, a quality at bat is not measured simply by the standard batting statistics such as batting average, on-base percentage, or slugging percentage, but by stats that show productivity regardless of result.

Source : gamechanger.io