Custom Oak Cycles 650B French Randonneur Project.

A handlebar bag was more aerodynamic than a Carradice saddlebag that extended just slightly beyond the hips of the rider (see photo at the top of this post).
is not the same as
there are also some evidence that the handlebar bag is oddly more aerodynamic than a saddlebag
.

The former is specific, you make out like it's always the case.

Having a rear bag which does not extend past the hips would drastically change the results.