Does anyone else have matchmaking concerns?

Made it from Gold 3 to Gold 1 in one day of grinding as a support main (Pretty much one-tricked Janna for 10 games), I was consistently getting low-mid plat teammates and enemies. After hitting G1 my MMR was 1813, which is above average (or was when I checked). After my promos, I started only getting matched with mid-high Silvers, but I was still playing against teams that were high gold or low plat. I'm just super confused on how I get matched with less skillful players as my MMR increases.