I guess I would need more info for the particular instance you are talking about. But if it is regarding the weekend storm. Even today we are still 4 days away from it happening and the upper air energy responsible for it to happen is still out in the Pacific Ocean, around 3000 miles from it's weekend position. So one should expect some changes with a weather event forecasted so far out.
While it may seem like a huge change to move the main band of snow from MI to OH, in the grand scheme of things, it is really not that big. Just change the track the storm will take after it makes it's turn to the northeast from the southern Plains by a few degrees one way or the other and that can change the placement in the eastern Midwest by several hundred miles.
I don't think the models are really any worse, although they do seem to be struggling of late. Plus, many of the systems this winter have been born from disturbances in the jetstream that become separated from the main jet. The models have fits with this scenario.
Hope this all helps!
-John