Mains: Taking stock of preseason predictions

From SABR member Rob Mains at Baseball Prospectus on November 20, 2017:

“It’s tough to make predictions, especially about the future.” —Yogi Berra

Everybody makes projections at the beginning of the season. We do, FanGraphs does, ESPN does, Sports Illustrated does. Many others. Maybe you, too. It’s kind of a silly exercise, in that it has no bearing on what happens in the coming season. A projection of which teams are going to win the six divisions doesn’t convey information the way that an analysis of a pitcher’s repertoire, or a hitter’s platoon differential, or a manager’s bullpen strategy does. But they’re popular and people like them, so we do them.

They have a short shelf life, though. Generally speaking, people don’t look at projections much once they’re made. For player projections, that’s a mistake. Projections from a good model, like our PECOTA, are a better predictor of both hitters’ and pitchers’ rest-of-year performance than their actual statistics until pretty late in the season. (Click on the links, or re-read the sentence, if you’re not familiar with this concept; it’s counterintuitive as all get-out.)

However, projections of team win-loss records … well, who really cares about them once they’re made? We know that the Twins and Diamondbacks did surprisingly well, and the Mets and Giants did surprisingly poorly. We don’t need preseason predictions to quantify that.

But rather than ignore them, let’s look back on preseason projections. Who did well? Who didn’t? Not that it means much of anything, unless you’re gambling on baseball, but just the same, it’s something.

Read the full article here:

Originally published: November 20, 2017. Last Updated: November 20, 2017.