I finnished s1 last act and was matched against plat/low dia this act for some reason, won 1/5 placement games and got plat 2. what the fuk, can somebody explain?

I’m a Jett main and I always make sure to entry but my team never follows even tho I ask them to. I’ll get a pick or 2 about 50% of the time I smoke dash in but even when I don’t I dash to get the info still before I hit my smoke. My team w...