How does the new MMR system work (SoloQ/DuoQ)?

So me and my buddy Sharkmask have been doing a bit of DuoQ lately. With 75 % winrate we are barely gaining any rating, because every loss is about -20 while every win is around +10. Even if the opponent team has a higher MMR we lose -20 points.
After looking at the numbers it seems that when you DuoQ you lose twice as many points from a loss, and gain half of the points you otherwise would from a win in SoloQ.

Heres a pic: https://postimg.cc/62p4P48M

It's hard to explain why a loss to a team that is almost 150 MMR higher means you lose 22 rating. This would mean our base loss rating is 11, since 11*2 is 22. Like the Druid in the pic gained 30 rating, which would be 15*2 if the above statement is correct. Why would he gain 15 as base value when his teams MMR was this much higher than ours?

Can anyone explain how the new MMR system works?