Better Matchmaking At Lower Ranks?

I'd think there are enough players at lower ranks to put better matches together.

I'm Gold 3 and had won 9 of my last 11 ranked matches (so MMR has to be on the rise). My previous games had been filled with mid-golds and even some plat 5's.

Then I solo queue and get a Silver 4 who bans the champ I'm hovering in champ select and deals 1.6K damage as Vayne jungle. I get a Silver 1 (okay) who plays Teemo ADC. And I get a Gold 5 Yasuo who goes 0-7 and AFKs.

Why the massive decrease in similarly ranked teammates and opponents?? My KDA on my champs is really good and I tend to get great post-game grades. It doesn't make sense.