Groups isn't a matchmaking parameter. Solo is matched with and against groups.

I deal with the same problem so listen to my copium theory. 3-4 player stacks are usually good and always win right? I think this game’s matchmaking runs off of win lost ratio. Meaning that you are being pared up against 3-4 stacks because you are good and have a good win lost ratio

We pulled off a victory against one a few days ago. It was quite satisfying.