One would think that a player with more kills and less deaths (dueling kills and deaths) would have a higher rating than a player with less kills and more deaths. That is not always the case--so what am i missing here?

You get more points for beating somebody with a high rank than you do for beating somebody with a low rank. I believe you also lose fewer points for losing to a highly ranked player than for losing to a lower ranked player.

ahh ok thank you.

It's the Elo rating system, if I'm not mistaken.