There’s a commonly heard axiom that goes something along the lines of: “He’s only going to get better with more experience.” But is that based on quantifiable data or is it a truth we’ve come to expect after gathering too many alternative facts on the subject? Spoiler alert: it’s accurate.
And thanks to the aging-curve research conducted by Jeff Zimmerman of FanGraphs, we actually know just how much better hitters get with age. The last time he ran plate discipline analyses was in 2012, so I tweeted at him asking if he thinks the curves have changed since then. If I get a response, I’ll update it here.
As you might expect, players tend to lay off more bad pitches as they gain experience. Hitters who debut at 21 or 22 years old *cough* almost all the Cubs prospects *cough* tend to have a nearly 3% improvement in O-swing rate (that’s swings at pitches outside the zone, so going down is good) over their first six seasons.