Back in March, several dozen websites, written by either professionals, bloggers, or, in some cases, professional bloggers, came out with predicted MLB win totals.
A predicted win total represents the number of wins this website or individual predicted for each major league team. These numbers can be easily compared to the Las Vegas line for each team (I used the one set by the Hilton) to determine if these predictions are worth our time, and, in some cases, our money. My goal was to determine which of the more famous sites, if any, outperformed the Las Vegas predictions, as judged by a few easy-to-calculate metrics.
Here are the sites I used: (if there are others that you’d like to compare, please send them along!)
O/U: The Hilton’s over/under for each team
BP: Baseball prospectus
TR: Team Rankings (caveat on the linked page: the site stresses their MLB predictions are a work in progress)
Zips: ZIPS projection system (espn.com)
PM: Prediction Machine
TB: Trading bases, an avid blogger and book-writer
Here are my metrics
MSE: Averaged squared error between the prediction and the win totals (lower is better)*
MAE: Averaged absolute error between the prediction and the win totals (lower is better)*
Corr: Correlation between the predicted and the win totals (higher is better)*
*For win totals, I’m use each team’s estimated win totals from here (I’m too excited to wait until the end of the season!)
Baseball prospectus appears to offer the only clear advantage over the Las Vegas line, at least among these predictions, as judged by a higher correlation and a lower MSE between observed and predicted values. As for team rankings & prediction machine, their results were both disappointingly bad. (Note: Trading Bases came into the picture after the fact, and also appears to be a clear winner).
Here are the Vegas lines and each site’s picks. In some cases, the total wins might not add up to 82 per team, most likely due to rounding errors.