This will be a closer match than people are expecting IMO. Bar sheer power, Bisping does everything better than Stann. I would still expect a Marquadt/Okami-esque wrestlefest from Chael. I'm neutral on this and don't care who wins, but would much prefer to see Sonnen-Silva II than Silva-Bisping (Silva KO1 Bisping)
I can't see it being close at all. Bisping has no power to keep Chael honest, his TDD will be nowhere near good enough to stop Sonnen, and his BJJ is not sharp enough to submit Sonnen. This fight will basically be Sonnen folding Bisping up into a ball and wrestling-humping him silly for the duration. Easy, easy win for Sonnen IMO.
You'll see a trend with people that pick against high level wrestlers. They are very confident and like to throw around the word "troll", but then when confronted with any consequences, they shut the **** up.
Sonnen should win a comfortable UD but I'd make Bisping a live dog. His takedown defence is decent. Rashad couldn't keep him down.