I think you probably should chop these down and start over. I think actually what you have is a mistaken identity on the tree itself. Shumard oak is often mixed up with pin oak which does not do well in our area. It prefers a more acidic soil (East Texas) and shows iron deficiency all the time in our area. They will live a while, but ultimately they look like this. I'm surprised yours is showing symptoms so early. You are lucky though, because often times the trees will get some size on them and then start looking like this, and that's sad to cut down a larger tree.
So, it could be just a mistake in the labeling, or it could be that the genetics of the tree are just a little more on the pin oak side. Oak trees have a lot of variety in their genetics and they cross often. 
You are in a good position now though to wait and see what an oak looks like this fall in the nursery and select it for that. You want to pick a shumard that gets the nice red fall color. And October, November, and even December are good months for planting trees. 

Let me know if I can help you further.