Trying to Figure out new Draft Queue process

Well since not many people play support, they won't put it into their secondary pick. I'm not entirely sure how the system works, but here's my theory on how it works:

So you queue alone while putting mid (primary) and support (secondary). During the matchmaking process, the system finds another person with mid (primary), BUT top as secondary. Now lets say someone else in the matchmaking process has top (primary) and say... jungle (secondary). Imagine another person has adc (primary) and mid (secondary) and the final person has jungle (primary) and adc (secondary).

Using the data from this example, it will put you in your secondary (support) 100% of the time since it is the only role left open by process of elimination.

Now, I know there are a LOT of different possibilities in the matchmaking process, but it makes sense that you would get support all the time if you get stuck in situations like this one.

~Hopefully this makes sense

HOWEVER, it seems this is incorrect T_T

I queued with some friends here were the results. Me: Mid (primary) support (secondary), Friend 1: Support (primary) mid (secondary), Friend 2: top (primary) mid (secondary) Data from the other people - Person 1: support (primary) jungle (secondary), Person 2: support (primary) adc (secondary)

So it turned out as - Me: Support, Friend 1: Top, Friend 2: Mid, Person 1: jungle, Person 2: adc

The 2 random people that appeared in out champ select seemed to have gotten the roles correctly according to my theory, but what throws everything away is that Friend 2 didn't get top and Friend 1 got top while queueing for Support/Mid. Still not sure why I got support rather than mid since there were 2 others with their primary set to support and no other primary mid. This means there must be something else to the process that determines roles that I am not aware of.

~Thanks for reading :) If anyone has some theory as to how this works, feel free to comment