It's because you lose too many matches... You could go -8 every game, but if you won the majority of your games you could make the bronze division. The same thing happened to me, I got rated at 1600 and was placed in the iron division because I kept getting bad teammates. My advice if you're tryi...
Great Drawings!!! :P As a suggestion maybe next video you could post a few drawings of "Halo Reach" characters... Keep it up :)