Mains: Taking stock of 2019 preseason predictions

From SABR member Rob Mains at Baseball Prospectus on November 20, 2019:

“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 who’s going to win the six divisions doesn’t convey information the way an analysis of pitcher’s repertoire, or a hitter’s platoon differential, or a manager’s bullpen strategy does. But they’re popular, 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 counter-intuitive as all get-out). 

But projections of team won-lost records…who really cares about them, once they’re made? We know Atlanta did surprisingly well, and the Orioles, well, nobody thought they’d be that bad. We don’t need preseason predictions to quantify that.

Read the full article here:

Originally published: November 21, 2019. Last Updated: November 21, 2019.