that's correct Larry if the plug is simply just sitting in the water.
but we usually apply a force to the lure as it goes thru the water to swim like a fish, any slaight differences in the balance of the plug can be magnified as the plug is moved thru the water. I took mechanical engineering in college and I'm sticking to it
all in all, the balance can be thrown off even more when the thru wiring hole is drilled, since it is rare that they will be drill to exact tollerances.
you can drive yourselves crazy with piciune stuff, they are just plugs.
I gotta go make some boxes now