If you are casting roadrunners pause your retrieve and let it flutter down over the top of structure.Also don't be afraid to let it go all the way to the bottom ,crank a few more rounds and let it go down again kinda like hopping it along the bottom.I catch more fish this way with a roadrunner than any other method and have used this technique for many years.My favorite rig is a 1/16 head with a black/silver swimming minnow.