Just some further checks (mostly for myself of the future when I moan).
So analyzing the last 20000 recorded matches (the last one in the set done on the 2017.06.01 9.10 AM), that should be a pretty large chunk.
Fun fact, the gaps between match ids are pretty often, it means a lot of players takes time to commit to a match (as 2nd players) and so the match can be in pending for long time.
A match was started on the 8th of February and was committed on the 22nd of May for example. But those are a minority of matches. Mostly the gaps is like 663040 to 663044 (it means three matches in the middle may to be completed later). Anyway analizing the last 20000 games in order of id, should put aside also those rare case of long waiting time between creation and result.
So ignoring those gaps, because a random sampling of a random stream should still be random, I got the following results. Considering a consecutive appearance like: if I have the series 51114 , 1 appears in two consecutive appearances twice. 514 and 514. This avoid to let count triplets, quadruple appearances and so on.
circle of death: 332
Barred spiral: 313
split team: 301
the seven wonders: 343
mind game: 269 (!)
set your priorities: 295
Now the expected value is 312 and since the sample is pretty large, things should converge to this value even considering that not all the matches are resolved in time, because one gets a random sample of a random sample.
If I simulate random assignments with the same size I get results varying from 320 to 304 more or less, not much more or much less unless I repeat the experiment over and over. Anyway the point is that the more the samples, the more the number should tend to the expected value.
What looks suspicious is the value of "consecutive" mind games (15% less than the expected value) and seven wonders (9% more).
Aside from that, the analysis (better than the last time, where I counted in a very naive way, without considering some factors), shows again that mostly the behavior is ok. Maybe what is frustrating is to have the same opponent __and__ the same map.
Still 15% or 9% of discrepancy from the expected value may grant a check, or maybe not.
I'll do the same by player though, so we may have more insights with the point of view of a player that cannot see maps not assigned to him.