Often times, when the oxen are pulling a heavy load and they stop, they will simply hold it where it is. Often times, that is, but not last Saturday. Just as I got ready to snap the photo, Pollux stepped back a bit.
What I was trying to capture was the way that the shoulder of the animal passes outside of the bow. Seeing it once really drives home the point about a yoke that's too small being better than a yoke that's a little too large. If the yoke is too large, the shoulder bone pushes against the bow and it can be painful for the animal, akin to walking across the floor on your elbows.
Anyway, this fine video by Tim Harrigan explains yoke fit better than I do. Watch and learn.