At work a couple weeks ago, my team was designing certain software components. In one particular area, the team wanted to go one way but I argued for a different design. I "lost" and we went with the design the rest of the team wanted.
Then yesterday, some input came from other teams, and the decision was made to refactor -- to switch to the exact design I had originally proposed. What did I do? Jump for joy?
No! I argued against the change -- against the design I'd originally wanted! Again I "lost" and we are going forward with the refactor.
I noticed this pattern and realized that in both cases I did not feel strongly one way or another. (I couldn't even write "lost" above without putting it in quotes!) I was really arguing because I felt someone needed to be contrarian, to defend the opposing view. Once I presented my opposition and others heard me out, I felt immediately better, as though an important role in the discussion had been fulfilled.
It seems clear to me that, within this team of folks anyway, I've recognized the need for the Oppose element and gravitate toward making sure it's filled.
You can really see how this can make teams effective once they get used to working with each other, since people will automatically gravitate toward certain roles, and others will recognize those. For example, I think people on my team subconsciously recognize that I like to play Devil's advocate and don't worry about me taking it personally when I "lose".
I think this is all discussed in the theory book, or at least on Melanie's website, but I just thought it was really cool to see it in action!