Confused by shirt yoke: why is the back longer?

[gem]

I'm finally getting back to work on my version of the shirt from Simplicity 4059 (which we previously discussed here).

I've decided to lengthen the front yoke by a couple of inches to get better coverage (which involved also redrafting the armscye and the gathered lower portion of the shirt). All is well on that front--good to go.

But. As I was cutting out the muslin, I realized that the back yoke is already 2" longer than the front yoke. Why is this? Do they expect folks' backs to be, erm, slopier?

Logic tells me I should also lengthen the back yoke, to keep everything at the bottom (where all the seams come together) fitting properly... but that existing extra length is really throwing me (I don't want to end up with it being baggy in the upper back). Why is it there, and what should I do about it?

Gramercy!!

[CenturiesSewing]

Quick flip through my pattern drafting book does not mention adding any ease to a yoke pattern.

Unless you have very forward shoulders and/or a "dowager's hump" I don't think that much extra length is needed.

Fold out the excess and just make sure the side seams match in length.