I haven't read about rating systems like Glicko or others, but i assume that:
If you win against stronger ppl -> Increases MMR by X
If you win against weaker ppl -> Increases MMR by Y
If You lose against stronger ppl -> Decreases MMR by ~Y
If you lose against weaker ppl -> Decreases MMR by ~X
Weaker = Average MMR lower than yours.
Stronger = Average MMR higher than yours.
Where X > Y
Currently, this is not working like that, and i have a few proofs. I play Order.

Order average MMR = 1577.66
Destuction average MMR = 1587.5
Avg Diff = 9.84 (Destruction higher)
Order victory, and i got +8 MMR.
Next match:

Order average MMR = 1617.5
Destuction average MMR = 1719.5
Avg Diff = 102 (Destruction higher)
Order defeated, and i lost 9 MMR
I lost more MMR against stronger ppl than what i get if i win against stronger ppl....
Its the first week since Ranked SCs relase, i know that and Rating System will change, but currently its working weird.