Mains: The one team PECOTA missed

From SABR member Rob Mains at Baseball Prospectus on September 28, 2017:

This turned out to be pretty good season for prediction systems in general and our PECOTA in particular. PECOTA thought that Boston, Cleveland, and Houston would win the American League divisions, with Los Angeles and Chicago taking the National League West and Central, respectively. It had the Mets with 86 wins, the Nationals with 85, and the Giants with 84, so we were close with our NL East champion, if missing badly on the Wild Cards.

We caught a lot of grief for suggesting that the Dodgers would win nine more games than the Cubs; the gap is currently 12. Similarly, our prediction that the Twins would have the second-best record in the American League Central was met with derision, and they’ll be playing in the postseason for the first time since 2010. All in all, a pretty good season for PECOTA.

The Mets and Giants projections, of course, were whiffs, but they’re whiffs just about everybody else had, too. And here’s another one: We projected the Padres with the worst record in the majors, at 68-94. Again, this was consistent with just about every prediction out there. And it wasn’t just algorithms like PECOTA. Human predictors were in accord. Of the 62 Baseball Prospectus staffers who participated in our pre-season predictions, all but two had the Padres last in the National League West. There was no team in the majors for which there was greater unanimity for a prediction in the cellar.

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Originally published: September 28, 2017. Last Updated: September 28, 2017.