Not sure if this has been posted yet, sorry still new . Here are the rankings for The Siege. I personally thought platinum was the highest , but I was wrong DIAMOND is !!
I am a GOLD II or III . Hope this helps. Also below is some examples on how the ranking works....
------KDA doesnt matter. Score doesnt matter. W/L does. if you're against lower ranks and you win, no (or very low) rank boost. If you lose : you'll probably derank. If you're against higher ranks and you win : you'll rank up. If you lose, you'll get no or very low rank loss.
Exemple : 5 man squad, all silver/gold losing to copper/bronze team = rank loss for everyone. You're really not suppose to lose, so you're not that good = rank loss.
5 man squad silver/gold winning against plat team = one rank for everyone. Because you're not suppose to win, if you do, you're good and deserve to rank up.
As for the ranks : Copper < Bronze < Silver < Gold < Platinum < Diamond.
Link to picture of ranks http://i.imgur.com/4VMxV6P.png