I know this post is from a while ago but I simply have to point out that I for one have NEVER seen a top player receive a legendary reward, let alone an exotic. On the other hand, many times i have seen a terrible player with a k/d below 0.5 receive a legendary reward and a few times, an exotic reward. Everyone i have ever spoken to also has this same experience with the rewards in crucible. That by itself shows that the crucible reward system is not random and that the lower players have a higher chance of receiving a reward than those at the top of the scoreboard.