why is my team always bad?

On my other account, i am ranked onyx in slayer and my team is always complete trash 95 % of time. I am dying every corner because of -Yoink- team

I am solo because all my friends hate halo 5 and i don’t blame em. But dont tell me to find a party to team up with because i prefer playing solo. Is it because ranking system is still inaccurate that people get placed in onyx or diamond that are trash?