As for dermabrasion, there's nothing really that complex about it. Think of your skin as hills and valleys. Dermabrasion basically takes down all the high points (the hills or shoulders of scars) so that it's shallower and closer to the depth of the valleys. Unfortunately you just cannot sand down that much skin because anything deeper than the reticular dermis and you will scar. There is a limit to how deep resurfacing can go. A better approach would be to fill the valleys, and get them as close as possible to the level of the hills. Then, when you do a resurfacing procedure it doesn't have to go as deep. Subcision and suction is well suited for this "elevating" of scars. There's also a pretty high "unpredictability" factor with dermabrasion which is a function of how you heal and the doctor's technique.
In general rolling scars do pretty well with subcision.