We joked about it all season long, but has there ever been a detailed explanation of why Alex got completely edged out of the show?

She didn't even appear in the "Aftermath" show at all.

My theory is this:

1) She sucked HUGELY and was completely overshadowed by Paul. As a result, they cut all footage of her and replaced it by highlighting Paul. It is worth noting that all of Paul's "fireside" chats were made during the time the show was aired, as some of his comments referred to things that happened in the "real world" between episodes (I also noticed that he started holding the brandy snifter properly after a lot of web sites made a BIG DEAL about it).

2) She probably had something in her contract that she HAD to appear in every episode. Actors often negotiate this into contracts so they don't end up "on the editing room floor."

3) The Aftermath show had the feel of something that was not in the original plans. I think the huge success of the show is the reason this episode existed at all. As a result, any such agreements as mentioned in #2 would not apply. Thus, Alex did not appear AT ALL.

Anyway, I'd love to read some more "official" explanations as these are just my theories.