I am trying to understand how going lower impacts frontal aero

When the snow melts I will do this with field testing, but I am trying to understand the math behind frontal area, especially how much would I save for every cm drop, assuming I am starting from a position where my head is way above my back. I understand that there is a low point where you will get diminish returns.

In this article (http://www.endurancecorner.com/Alan_Couzens/bike_fit_4) the author claims “For an average 6ft tall cyclist, moving from a 73 degree seat angle to an 80 degree seat angle will decrease the frontal area by ~.03m^2,”. This is about a 10cm drop according to him. So let's say .003m^2 per cm.

I then put this .03m^2 in a power calculator and it says that if I reduce by .03m^2 I could save 15watts.
15 watts, 10cm, about 1.5 to 2watts per cm drop

Does this make sense ?

If I take the widest point of my shoulders when crouched/compacted is say 30cm * 1cm lower = .003m^2. Does this make sense?