I think that the problem is that they use level as the basis of matching. They should use power level for matching and nothing else. People should only be matched if they are within 5k power of each other. That difference is doable for a small player to win if they have a good line up, and know how to play the game. Anymore and difference and you get the results that people are seeing. 5k difference also gives the program some wiggle room in matchmaking.