Team Doubles ranking weirdness

I played my first ten team doubles games with the same player. For those ten games, he had a cumulative kda of -2 and I had a kda of +2.7. I had 111 kills and he had 77.

Yet somehow he got platinum and I got gold. Any ideas as to how this might have happened? It’s obviously not a big deal I just would like to understand how it works.