About a week ago, I went over the stats I use when examining hitters during the offseason. Today pitchers take center stage. With Pitchf/x and now Trackman publicly available, I find it quite a bit easier to evaluate pitchers and the changes they make. For pitchers, I have one sparkling new main source and one old standby.
Pitchers are so much easier to evaluate compared to hitters. If a pitcher gains a couple ticks on his fastball, we know right away within a couple of pitches. If a hitter can no longer catch up with a 96 mph fastball, it may take a few months to know for sure and even then, we may not be sure why. Here are the tools I use to help find pitchers who have changed for the good or the bad.
Pitch Type Metrics
Ever since helping Eno dive into pitch-type metrics, I’ve determined that I will evaluate pitchers using this type of data. Even though it took a while to hammer everything out, the final results have been extremely promising. We can now determine what each small pitch change will mean for each pitcher and how pitchers can improve their results. The complete write up of the process is available, but here is a quick summary.
- The key change is to give each pitch an ERA value (pERA) based on the pitch’s swinging strike and groundball rate. All the values are based off the average values for starting pitcher. Closers will have higher grades because their stuff plays better coming out of the bullpen.
- The pitcher’s control is determined from their walk rate which is separate from the pitch grades.
- I’ve put each pitch on the 20-80 scale with 50 being average, 80 great, and 20 horrible. For starters, target pitchers with three average or better pitches. For relievers, they just need two pitches.
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