Credit where credit is due . . . I think the Brigade was good at doing three things:
(1) Not mentioning their alliance to anyone else. This should be easy, but lots of alliances have gone down because someone had loose lips.
(2) Making "fake" side alliances with other houseguests (Lane/Britney, Matt/Regan, Hayden/Enzo/Brendan)
(3) Not getting paranoid. They danced on the edge a little - they were clearly worried about Hayden/Kristen, Matt/Regan, and Matt in general, but it never got to the point where paranoia caused them to self-destruct.
Having said that, I think they were incredibly LUCKY as well. They are lucky everyone else was dense and clueless. They are lucky no one had a spine. They are lucky that people liked Enzo. They are lucky that Brenchel hated Britney/Monet and that everyone else hated Brenchel. They are lucky that Andrew was socially awkward. They are lucky there was no ED in the house.
They are incredibly lucky that Enzo brought Matt in as the brains - if Matt had not been in the Brigade, he would have taken it down.