Malcolm Gladwell has an outstanding article in this month's New Yorker entitled "How David Beats Goliath." It is an excellent primer on the concept of unlearning and I can't recommend the article highly enough. If, however, you don't have time to read the full article here's the operative quote: "When underdogs choose not to play by Goliath's rules, they win."
According to some scientific research Gladwell cites, "David's" (i.e the underdog) winning percentage against "Goliath's" increase from 28.5% to 63.6% when they play by unconventional rules!
Think about that for a moment, folks. What the article is really telling us is that if we want to win against a bigger, stronger and more well-funded opponent one of the first things we should do is "unlearn" the rules.