Scoring

Why is it that when two or more couples are tied on a score, the judges scores are unfairly weighted? For example the judges scores this week equated to A&N - 5, G&A -4, L&K - 4, B&J - 4, K&C - 3. Had three teams in the middle scored differently, then K&C would have received 1. It makes no sense that a couple could top the leader board with a perfect score and still end up in the bottom two.