Based on Wanderlei being the primary aggressor, and Sonnen being relatively passive in his demeanor with arms folded, I think it was real emotion erupting. He seems like a very proud person, who is truly angry at Sonnen's personal barbs against him and Brazil. Had Sonnen been really taunting Silva or more of the aggressor I could believe it being planned/calculated to sell even more PPV buys. The other thing that struck me was the appearance of Silva's coach/friend punching Chael several times from behind; i wouldn't expect that as part of some planned fake scuffle to promote fight or TUF interest.
Sonnen is by and large a very mediocre fighter in the UFC (largely one dimensional fighter) and the fight against Rashad was flat out an embarrassment. But he is witty, funny, and great at promoting fan interest. I can't see him lasting more than half of a round in a truly engaging slug fest, much less winning the bout in a standing fight. Silva is definitely not the fighter he was even just 5 years ago, but his standing game is far better than Sonnen's and he is one of the fighters that has that true killer instinct and will not hesitate to jump on an opponent to finish the fight. He undoubtedly prefers to stand and throw bombs, but I am not sure that he can stop Sonnen from taking him down and keeping the fight there for most of the time.
