Sarris: Why is it so much easier to project hitting than pitching?

From SABR member Eno Sarris at Sports on Earth on March 5, 2014:

Whether you’re evaluating your fantasy team or thinking about the future of your real-life team, now is the time for your favorite projection system to shine. Using past numbers, weighted to generally favor the most recent year but also to take input from early in a player’s career, these systems try to tell us the most probable outcomes for the upcoming season. Right now, they’re all we got other than spring training updates and impossibly useless results.

Unfortunately, those projection systems know a good deal less about one half of the game than the other. Pitchers remain a mystery.

If you test projections against actual outcomes, you’ll find that they do a decent job for hitters. Projection systems can explain roughly two-thirds of the general variability for their production, year to year. That’s much better than looking at just last year, which only tells you about half of what’s about to happen this year.

Pitching? You’re lucky if your fancy projection system gets anywhere close to explaining half of what’s coming this year. Many projection systems don’t do better than explaining one-third of the variability in the projected year.

Read the full article here:

Originally published: March 5, 2014. Last Updated: March 5, 2014.