General DiscussionQuestion on how party ranks work.

the way mmr works is the total (5) players on one side must = the total (5) of the oposing teams mmr or close to it

but wen u party u will always vs people close to or higher of your highest party members mmr

Don't listen to the guy above since both of his statements are completely wrong.

Suppose we have 2 groups of 5 each (a potential match up) and we know their MMRs.

Valve uses mathematical models to compute the "probability" that one particular team will win using what is called "pattern recognition". As input to the equation, it uses the 10 MMRs, and the model is based on past-observed groups of 10 MMRs and who won what. They use a particular algorithm called "logistic regression".

http://en.wikipedia.org/wiki/Logistic_regression

Just think of it as a magical box. You give it 10 numbers (in the range of MMR, i.e. you don't give it -1000 or 70,000), and it gives you an approximated probability that is far more accurate than wild guesses or even what a human could guess based on those numbers.

Valve then uses more ad hoc algorithms (i.e. just "rules of thumb") that jumbles together various other practical metrics when deciding whether a match up will go through. It includes things like how long have users been waiting. If too long, consider letting unfair matches go through for the sake of playing the game.

In the end, your team composition is pretty random. Any regularities in teams seen comes from the concidental fact that their algorithms deem those fairer match ups than other match ups in terms of winning chances (which shoot for near 50%) and also based on the composition of people searching for matches. E.g. if everyone searching were 5k, you'd only see 5k. There aren't many 6k, so even if you have 6k, you almost have a 100% chance that you will not have another 6k on your team - he will be on the other team to offset you, a rarity (as he is too). The main point is that these are not features of their algorithms, they are features of the quantity of each type of player searching.