Question on ranked values

So me and my friend have been queuing val much more recently, and both managed to climb to platinum 3. However, our lobbies have many differences. I am stuck in lobbies filled with mostly diamond (some ascendant) players and his lobbies are mostly platinum and some gold. For some reason, even when I perform the same if not better in my respective lobby, he gets more rr? Fastpanda is me and silly goose is my friend. I got 21 rr from my game and he got 25. I was fine with the ranking system until I got placed in ascendant lobbies for my rankup game 3 times in a row.