You've said this before, but this time recognized that any standard, while somewhat arbitrary, is better than none. Your sliding scale makes sense, but requires memorizing the 5 parts.
Plus I think one of the key measures of a "quality" start should be 6 innings. The Sox have played just 21.6% of the season, and commentators are talking about overuse of the bullpen even though the Sox have 9 bullpen pitchers because their rotation averages 5 innings per start. If 4 scoreless innings becomes the standard, the Sox should consider bringing back Swihart so they can go with 10 position players and 15 (or is it 16) pitchers.