Absolutely no one likes to start a match in Overwatch and then immediately feel outmatched. It’s easy to look at the game’s upcoming group finder feature as something tailor-made to produce just that; suddenly it’ll be easier to form full groups and just stomp the uncoordinated group of randos on the other side. But a new post on the official site explains that this is unlikely, especially as the game’s matchmaking system already assigns a win probability to the match and simply doesn’t create the match if the odds are worse than 60-40.
The whole post details lots of math and systems going on behind the scenes of the matchmaker. Rating changes are unaffected by your group and are entirely based on your projected odds of winning, your overall performance, how long you’ve been playing, and so forth. Meanwhile, full groups of six players are already overwhelmingly likely to at least be matched against other teams consisting of at least one pre-formed group, so the odds of this dramatically changing seem low. If you want to know about what goes on beneath the hood for Overwatch matchmaking, this would be a good thing to read.