Combine flour, oats, brown sugar and cinnamon. Cut in cold butter until it resembles coarse meal. Stir in pecans and set mixture aside. (Two cups of this mixture will be stirred into the sweet potatoes)
Drain the sweet potatoes and cut into 1 to 2 inch pieces. Place the sweet potatoes into a large bowl and toss them with 2 cups of the above mixture. Stir in 2 cup of fresh cranberries that have been washed and allowed to dry.
Spray a 9 x 13 inch baking dish with a non-stick spray. Press the sweet potato mixture into the pan and top with rest of the crumb mixture .
Bake 45 min to an hour at 350 degrees. Until heated through. Let set 20 minutes before serving.