The slats in the wing have nothing to do with decreasing drag. They do however allow the boundry layer of air to "escape" thus bringing the "laminar flow" air to a lower level and better able to contact more of the surface area on the kicked-up part of the wing. The term Wing is a poorly chosen name that we all use. "Air deflector" describes it more accurately.
The above is from Mr. Epp himself about the slots. I thought there was another more detailed post from him about it, but this is the only one I could find for now.