There's a good degree of lazy in all of us. As such, I have really enjoyed the good folks at Beyond the Bets tracking the success of our underdog wagering theory for Major League Baseball. Their latest post is here. The original academic paper is here, it came out in print at Applied Economics a few months ago.
In short, there are a number of reasons to believe that betting on underdogs early in the baseball season will generate persistent profits. It was true over the eleven seasons we looked at, it was really true last year, and seems to be going well again in 2012. Through the first 60 games this year, blanket betting underdogs would generate a profit of 10.31, a rate of a touch under 17%.
Insofar that the viability of a theory is its ability to predict, we've generated a pretty good one here.