Well in your original post you stated you had a tough time in both matches and in one you died a lot. Yet you somehow expected to get higher SR gains for those two games. So it does sound like you don’t understand how it works.
If you want to debate it then my opinion is that no you shouldn’t get high PBSR gains on matches where you do not play well, even if you played well in other games.
Additionally, if you just scrape a win, then no you didn’t outperform at your rank in that particular match up.