when you win you get matched with worse teammates at higher levels
when you lose you get matched with better teammates at lower levels
good people with less skill will often feel better than bad people with more skill especially when the latter is inconsistent.
Basically you say "So yesterday I won 7/7 games.. some (2) were a bit hairy and won from a throw" but in fact the truth of the matter is that your 2 hairy games where you won by a throw and something about you or your teammates made the difference in a game you should have lost is what really matters. You won the games you weren't expected to. You made a positive difference somehow or at you didn't make a negative enough one that you could be stopped. These are the two games that actually matter.
Your other 5 games just make the 2 or the next 2 miracle games possible. outside of this they are just warmup rounds, worthless musings. Winning those games on the short bus are the most important thing you can actually do if you want to raise your matchmaking level.