47 min draw, lose rating while other gains rating?

As the title says.
Just had a 3s game on my priest with crosskill within first minute, making it a 2vs2 that went on untill draw. But the other team, gained +16 while we lost -16.
We topped dmg by miles, which i thought would determine the winner in the end. Either that or lost rating for both.
What is the logic behind 1 team gaining rating and 1 team losing?

did your teammate die first? perhaps that's how it determined who won/lost.