That's all you needed to say. You're not a thrower, right?
Therefore, your opposing team has 6 potential throwers in it, yours has 5. On average, you will win, then. Right?
I don't play on SEA servers, so maybe there is some pervasive issue that means population statistics don't work, or that number of games played to reach your appropriate SR is really large, but generally, persistence, optimism and self improvement will contribute to increasing your SR. Queuing with like minded players should speed up that effect, too.
From what you've written it does look like SEA servers have issues, and in that case my advice is moot. I guess the only solution is to grab a 6-stack.