Sonnen isn't worried or scared by this "new" Silva. And Silva isn't suddenly loosing it. The bottom line is, this is the real Silva and it's finally coming out. He has been holding back, but it's how he felt all along.
Since it's how he felt all along, but only recently decided to voice it, means it won't be an emotional factor that detracts from his performance.
However, for Sonnen, while it may not bother him, it's a totally new angle that he will have to think about, that prior to, he didn't. That can work against him.
All of that being said, MMA is really simple. In a 5 round fight like this, the better all around MMA fighter will win. And that is clearly Silva. He was the better in the first fight and he won, he is still the better in the second fight, and will still win.