Teammates during promotional games

Now, you might say I'm just salty and I am, I'll admit that, but I truly believe that there is an issue with the matchmaking during the promotional games. Maybe it is just me but it seems that almost every promotional series, Riot matches me with auto-filled players and people on a losing streak. However, I would almost instantly go back into promos because the teammates I get as soon as I leave promos are much better. I don't really understand the system but I just feel Riot makes promos really hard to win, which makes no sense because if I am already winning against people in a higher division than me, it should be obvious I should be able to get that rank. Maybe this is just me, so please give me reaffirmation or give me something that I can agree with so I don't lose my mind at this company.