Um... I'm hoping I read the dates on these posts correctly but for the last two seasons ( 7 and 8 ) Arena division placement has been SOLELY BASED ON YOUR WIN/LOSS RATIO, in other words you have to WIN and kills/rating does not mean ANYTHING anymore. Get with the times people... I almost want to go back to bungie.net after reading this...
In other words, you are probably in silver because you may get high ratings but since those do not matter at all anymore you probably have a low win/loss ratio.
I'm guessing like 55%?
It also depends on how many games you have played, the more the better, for gold I'd say get like at least 60% w/l with 50+ games perhaps