What's interesting is that I was told explicitly that they personality issues were with American players.
Insight was given into the Mix decision, yes. I want to be careful with what I say here - so I think the easiest way to explain it is that PV expects his guys to be a family. You are all in or you are out.
I'll speculate (and this is nothing but pure, made up, 100% pure baseless rumor and speculation) that Mix threw a bunch of teammates under the bus in a very public manner after the Open Cup loss. That could be one way to get exiled.