Catching up on the Overwatch [official site] forums, there's a post by the game's director, Jeff Kaplan explaining a little more about matchmaking. The part which stood out to me (and other people, judging by other articles online!) was that Blizzard have disabled the "Avoid This Player" function from the game because of what it does to matchmaking when people use it avoid skilled players.
Here's the full explanation after the jump.
N.B. This is the only time I have ever felt sorry for a person who is good at sniping in an FPS:
"One of the best Widowmaker players in the world complained to us about long queue times," said Kaplan. "We looked into it and found that hundreds of other players had avoided him (he’s a nice guy – they avoided him because they did not want to play against him, not because of misbehavior).
"The end result was that it took him an extremely long time to find a match. The worst part was, by the time he finally got a match, he had been waiting so long that the system had “opened up” to lower skill players. Now one of the best Widowmaker players was facing off against players at a lower skill level. As a result, we’ve disabled the Avoid system (the UI will go away in an upcoming patch). The system was designed with the best intent. But the results were pretty disastrous."
It never occurred to me to use the system to avoid good players. What a fool I was!
The rest of the post is an interesting read, regardless of whether you like Overwatch because it looks at the ideas behind matchmaking in general as well as Overwatch in particular. It's things like how waiting longer for a "better" match sounds attractive in abstract but doesn't quite match with reality because if you get those perfect match-ups 50% will be losses so you've waited a long time to have a negative experience - or at least more negative than a win. At that point it sort of doubles down on misery even though it's how the maths of the situation should work.