As I understand a deficient EQ is usually supposed to be thought of as a suBathmateaximal level of blood circulation in the penis while being erect, which is what you also seem to suggest. Therefore one would have to conclude that your erect penis is softer than he would be under optimal conditions, thus not allowing to be considered as "fully" erect. But I think I see where you are coming from because like you I'm normally also with lessened EQ able to get to max blood circ. level and to measure the expected inches. But for once it's more difficult to get there and moreover it's even more difficult to hold that level upright for an extended time line. Is that what you're saying? If it is we should clarify the def. of a "bad" EQ as appearing in different variations.
But still - at least intuitively (never checked it) I would disagree with your assumption that length is not affected proportionally to girth, i.e. measurements of the two measures relatively differ from each other under the same conditions. ok, to make it more K.I.S.S.
: given a certain EQ level, you should also measure your usual length if you are able to measure your usual girth.