Re: DOTA 2 Skill Level Calculations
It's been explained on the dota2 dev forum that they use a pretty standard rating system - every player has a hidden MMR rating that they start with (depending on how they answered the initial question on how skilled they thought they were).
Winning games increases your MMR, losing games reduces your MMR, no other factors are taken into consideration.
In general I've seen numbers that suggest the top 15% or so players are "High" skill, the top 3% are "Very High" skill, and the rest are "Normal". Some guy did a scrape of a hundred thousand games off the DOTA2 server, similar to what DOTABUFF does, and just sorted it by game skill level and found these ratios.
From personal experience, it took about 20 wins to advance from Normal to Very High Skill, something like a 10 game win streak, and then a few losses and few more smaller streaks.