Only gained +1 MMR for a win?

Me and my friend were playing some 2s tonight, and I had the RL Tracker site up on my laptop while we played. We had several wins/losses gaining/losing 9/10 MMR each game as expected.

Except in our last two matches, he only got +1 MMR while I earned +9, then on the next match I only got +1 while he earned +9. We didn't quit or forfeit any games during this session, and MMR ranges for opponents were pretty close to ours throughout. Biggest gap between two players we saw was 100 between them (a D3 with a D1 iirc).

I'm sure this has been asked before, I did Google but couldn't find anything beyond MMR displays bugging a bit on Bakkesmod. Nothing on the RLTracker though.

Edit: This is a link to my profile on RL Tracker where you can see my MMR gains and losses from tonight.