Zimmerman: When plate discipline sticks

From SABR member Jeff Zimmerman at November 20, 2017:

A few days ago, Jake Leech asked me if Zack Cozart’s 2017 improved plate discipline would stick into 2018.

He saw quite a bit of improvement with his K%-BB% drop by 6% points.

Note: I like using K%-B% to get an overall value for a hitters plate discipline. Early this year, I investigated what early season stats point to a true breakout. K%-BB%, along with launch angle (FB%), are the two key factors to focus on.

The Steamer projection has his K%-BB% regressing closer to his 2016 values than his ones from 2017. This is how projections work with previous season stats having some weight along with some regression.

From the Tweet thread, I wondered if some underlying plate discipline values (Pitch Info swinging and contact values using inside and outside rates) which could point to a hitter keeping more of the gains.

I found all the hitters (min 200 PA) since 2008 who saw their K%-BB% increase by 7.5% in one season and then their value in year three. I started with hitters who saw a 6% change like Cozart. I couldn’t find a nice year-to-year trend. I did find one at 7.5%. The 6% values generally lined up but 7.5% value more obvious.

Once I found the hitters who improved their plate discipline, I grouped the hitters by who kept the improvement going forward into three groups. Here are the results.

Read the full article here: https://www.fangraphs.com/fantasy/when-plate-discipline-sticks/

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