What factors go into increasing your rank in competitive?

I'm not necessarily complaining about the ranking system as I'm sure there's a reason behind what's happened.

So my buddy and played a good 30 or so matches in doubles over the past 20 or so hours(we slept in between). We literally won every game but maybe 4-5 of them. I only had 2 division ups and even divisioned back down on one of the losses.

I guess I just want to know what factors go into moving up in the system? Being on a 15 game win streak and not moving up in ranking was a little off-putting.