If you check his game from roughly a week ago you'll see that he won multiple matches back to back, facing no opponents. This player was clearly manipulating the network to circumvent playing against other players in order to win matches to get to Legend. I have already reported him in game and on this site, but I didn't feel like that would be enough. There are others in the party with him who also took part in this as well. I'm unsure which player was the one manipulating the network, but it doesn't matter as they all partook in this action.