Just to avoid what some of us consider a quality start and what is defined in the ML as quality start.
ML definition of QS=Starting pitcher must complete at least 6 innings and not give up more than 3 earned runs. If a pitcher did pitch 6 innings and give up 3 earned runs every start for the entire season, he would have a ton of QS, but would end the season with a 4.50ERA.
Personally, I would change it from 3 earned runs to 2.