Every single game I saw rank that are unfair and impossible to win in arena rank matches
Best thing to do is post in the Matchmaking Feedback topic ( pinned at the top of this forum ). If you link up some of the games you have issues with, Dr. Menke should be able to feedback the reasons for the the rankings you were seeing. Folk at 343 will be finishing up for the holidays, so it might not be until the new year when you hear back