Some short goals in matchmaking are:
Maximize Player fun ( )
Making it fair
Player skill follows a bell curve, as players play more games the bell curve shrinks. Rating needs to be fast. (as shown in Warcraft III where few games can skyrocket your MMR) Gaussian Density Filtering allows blizzard to update your MMR after every game quickly. The rating is put on every player, team and party. (Easier when players stick on the same teams) Teams are made before the match actually starts. The longer you wait for a game, the higher the disparity in skill will be.
For team games, if you are together with the same team, the MMR follows that team forever.
Games kind of lose the community feel if you simply jump right into game without interaction first. (cough cough brood war vs sc2)
"Want to make you feel like you have a new rating every season." (evil laugh)
They added a placement rating, asking questions like "when do we move you from bronze to silver?"
Placement rating is where your change in MMR starts evening out (he wasn't very specific about it)
Expanding search is bullcrap, after a few seconds the thing just says expanding search. (I'm sure you all knew that though)
He also mentions that win ratio is irrelevant, ratio is only supposed to change away from 50/50 if you are at the very top or the very bottom.
( )
"We don't want players to focus on league promotion, but rather getting ranks in their division."
"We wanted leagues because sports have leagues and it kind of makes it cool."
"Giving people ranks a leagues motivates players to play better."
"We wanted leagues because sports have leagues and it kind of makes it cool."
"Giving people ranks a leagues motivates players to play better."
( )
An example about promotion is that you can get from bronze to mid range diamond MMR in about 60 games. (I'm assuming he meant wins)
One of the problems they had was ratings getting inflated, so they put a tip at the ratings based on the number of people who actually play. This lets a player with a high skill rating find games faster. He also hinted that zerg takes more skill to play than that of protoss and terran.
I don't think I really got everything he said (he was pretty quiet at the end when answering questions), but I think I got the main points. I'm sure shindigs would've made a more detailed blog post, but he didn't show up to the presentation because he was busy with something else (killing esports? ?)