Well, I try to avoid cherry-picking. For every pitcher, I look at the same things. ERA (to an extent), ERA+ (much better), xFIP/FIP (good for predicting an outcome), K/9, BB/9, occasionally hit/9 and IP if we're talking about full seasons. Those can be applied to every pitcher and you get an idea of how well a guy pitches. What if the pitcher plays in Yankee Stadium half his games and is right-handed? The place plays like a bandbox for lefty hitters and he gets to face the AL East in half his games and maybe the Yankees defense is awful. What if the guy pitches half his games in Dodger Stadium and then gets to face the often weak NL West hitters and what if the Dodgers are the best defensive team in baseball? What does QS really tell you about those pitchers? What about a guy who pitched in the late 90s versus a guy who pitches today when run scoring has dropped around a run per game? Continue ad nauseum. By using a small sample size (~30 starts) and by using a stat that is nearly 100% arbitrary (again, what is a "Quality Start"?), you are hindering your analysis for no good reason. You can take offense to that statement but you shouldn't... it's just the truth. Yes, guys will fluctuate from start to start but if you draw from a large enough sample size (say, ERA+, K/BB per 9, and IP), you'll get a much better idea of what kind of pitcher you're looking at. There's just no reason to look at the Quality Start stat. There are much better options out there.