BCS Rankings: How does that work?

Does anyone understand the logic behind the BCS rankings? I definitely don’t. I have one for instance that baffles me.

In week 10 #3 Auburn played #4 Ole Miss. Based on their ranking who would you expect to win? Well, if you just look at the numbers Auburn should have beat Ole Miss, and they did. Ok.

In week 11 Auburn remained at their #3 ranking, but Ole Miss fell to #11. Why? Ole Miss was ranked one position lower and lost to the better team, isn’t that what’s supposed to happen? Right. Ok, let’s just leave that there.

We’re still in week 11: #3 Auburn loses to unranked Texas A&M. Ok, Auburn should fall big based on what happened to Ole Miss the week before, right? No. Auburn falls to #9 and Ole Miss is at #10. Can someone explain that logic, please?

#3 beats #4, #4 falls to #11.
Unranked beats #3, #3 falls to #9.

I don’t get it.