I love this because it's so true, and it's exactly how I approach combat in RP. 8D
I basically just try to think about which will make a more entertaining story. Which is the more interesting outcome? Sometimes, it just creates more interesting plot hooks to have my character lose! Sometimes, that victory can be the more interesting choice.
But I don't really care who wins or loses, because I have no personal stakes or pride in the matter, and if it's obvious my partner reallyreally wants their character to win, I'll just have my character lose. xD Even if my character is more competent. Because even skilled characters make mistakes. (Maybe they're sleep deprived? Maybe they slip on a patch of ice? Etc.) But yeah, I pretty much just roll with the flow of the story and try to think beyond winning and losing and more about whatever will better drive the story, be the most fun for everyone, and offer the most character development.