I really like Andrea this season, but I think she failed to see that she's a threat herself (and I completely recognize that and give her credit for it).
She played a hard game, has the Idol, and her downfall.. I would say... Is probably too trusting of her alliance members, even though she DOESN'T have a good overall relationship with them. For example, Dawn and Cochran are tight, and that's why they will never vote for each other and completely trust the things that they tell one another. For Andrea... she simply TRUSTED too much, with people whom she isn't even really close with. She thinks she's close with Cochran, but doesn't even tell him anything or strike a F3 deal. She wants to be close to Eddie, but yet continuously kept him on the outside.
I think Andrea lacked the social game and the EQ to deal with people, which Cochran shows how well he has done it this episode. Completely beautiful blindside, and Andrea had it coming for constantly mentioning about the blindside. One thing you learn on Survivor... you don't mention about blindside first, unless you are the ring leader... or you are sure you have a couple of people you are ABSOLUTELY trusting. Andrea thought she had a tight group... but obviously that's not the case.
Sad to see Andrea go... but like all other more memorable players... let's embrace Malcolm and Andrea for another third showing in this game... soon. -_-