The purpose of a balun is to isolate the antenna from the feedline so
there is no RF flowing on the outside of the coax. If you truly are using
a balun it should make no difference how it is connected. But if your
balun is doing its job there is no RF flowing on the vertical 22' section
because it is isolated from the antenna by the balun.
Some designs may use a 4 : 1 UN-UN at the feedpoint instead. The
difference is that now the coax shield is connected to one side of the
antenna. (With a 4 : 1 balun the shield is connected to the center tap
rather than to one end of the winding.) In that case it may make a
difference how the transformer is connected. The main reason for
using the unbalanced connection and letting some of the coax radiate
appears to be to improve the impedance match on 15m, where the
original Windom design tends to have a high impedance. In this case
the length of the coax section (which becomes one side of the antenna)
plus the length of the other side of the antenna needs to be resonant
on 15m, and that detail will depend on the actual wire lengths of the
design you are building.
Note that the actual current flowing on the 22' vertical section is pretty
small, and contributes little to the radiation pattern on most bands.
(Contrary to the claims of some manufacturers.)
A good article on the Off-Center Fed Dipole from W4RNL is here:http://www.cebik.com/gup/gup9.html