If Mapou's playing, then we could actually afford to have Debuchy providing his more wing-back style as (hopefully) common sense would say the entire back line sort of shifts a bit to handle for Debuchy being further up the pitch with Saylor moving more to cover for MD, Colo shifts more to the right and Mapou shifts as well.
But honestly, Simpson looked good - I think MD would be fine to just curtail some of his forward runs as much.