Difficulty Spike in Promotional Series

So, Season 7 has begun, and for the first time, I'm beginning a real ranked grind. I've played for several years now, since the middle of season 4, but that was mostly normal games with a bit of ranked if I had time. However, this year I do have the time to invest in ranked, and I'm finding myself at one hell of an impasse. I've been practicing for years (obviously) and during a significant amount of that time, I've been forced to play with high plat/low diamond players because my friends were at that rank. Now, obviously, I don't consider myself deserving of a higher rank; I know it is earned, and not given. However, I feel like Riot's work on soloq balancing seems a little... off. The game is team based, obviously, and Riot wants everyone to know that, and play the game with the intention of cooperating and working together to win games. This is, overall, an excellent theme to put behind a game. Nothing feels better than working well with a team to communicate and clinch a win. The concept that a team must work well together to win is fine, most of the time.

Except when it comes to promos.

Promotional series are, and without a doubt, have always been one of the biggest headaches in ranked, simply because of the amount of weight placed on them by the tier system. I understand their purpose; without promos, pretty much anyone could achieve any rank simply by playing long enough. However, I have begun to notice a trend in my promo series. Every time I get into a series, I end up in my secondary position. Now, I could understand that, if not for my games leading up to the series, as nothing changes in my position selections. From 0 LP Silver 1 to 100 LP Silver 1, I played somewhere around 12 games. One game was support (by choice, not autofill). One game was as jungle, again, as my primary role, not by autofill. The other 10 games were all mid, with mid as my primary. This is a bit better than usual; I generally get secondary position about once every eight or nine games and autofill once every fifteen. However, in my promo series, I got jungle (as a secondary) all three games in a row, despite changing nothing about my role selection. I wouldn't necessarily mind this once or twice; I know mid is a popular position, and that I won't always get it when I queue up for it. In my opinion, it would be significantly better if there was another protect (similar to autofill protect) which guarantees a player his/her primary role after playing his secondary role. Alas, I digress; there is a much more significant issue at hand, which has a significantly larger effect on the game.

Whenever I enter a game in-series, the quality of my teammates seems to fall significantly compared to any other game, despite the fact that the rank of the game I'm placed in is significantly higher than usual.

Upon looking at my match histories, I came to the realization that in all 3 of the games in my last series, I was not only pushed out of my primary role, I was matched against summoners who were 1.) in divisions far exceeding mine (mainly mid-high gold and even low plat) or 2.) had been in divisions much higher than mine in the previous season (again, high gold or low-mid plat.) Now, I understand that players might still be stuck in silver from their placements this season despite being higher last season. I understand that some gold players might have MMR low enough to justify being placed with silver players. Rank really does not phase me. However, it seems as if my teammates consistently drop in quality, to a point of near ridiculousness that cannot be simply dismissed as luck. In the games leading up to my series, I never had more than two or three players lose lane hard or feed before the roaming and teamfighting came in. The games were well balanced, the players were ready to go, and there wasn't really much in the way of toxicity. However, in my series games, it was a completely different climate. Every single game, my team had universally lost lane before the seven minute mark, despite my efforts to apply jungle pressure. The teams fed hard, flamed frequently, and generally made the games both miserable and unwinnable from any practical standpoint. Unfortunately, I feel like this is completely isolated to games played in series, which is quite concerning, as the reason I've finally been motivated to make this post is at the behest of friends who have experienced the same phenomenon, which, to them and myself, appears to occur in nearly every promotional series they undertake. It honestly seems as if the game is intentionally setting us up to fail, which is neither fair nor fun.

TL;DR: In series games, I'm consistently placed in a secondary rather than primary role, with teammates and opponents from higher divisions and tiers than usual and teammates that are generally more toxic than anyone in your average ranked game. It feels like I (and friends, who have corroborated the theory) are being set up to fail in promos, which really kinda sucks. If you feel the same, please feel free to share, and if you have an explanation or what not, please share it so I can understand the situation better.