Comparing Rookies’ Hitting Prowess to Veterans’

Yesterday The Hardball Times released its annual compendium of analysis, commentary, history, and fiction. I was lucky enough to be featured. My contribution show how you can use Empirical Bayesian analysis to compare rookies to veterans using their rate of Barrels per plate appearance. This tactic allows evaluators and fans to get a sense of a player’s true talent level even if they’ve hit only a handful of times in the Major Leagues. It also allows you to compare rookies like Miguel Andujar to veterans like Giancarlo Stanton.

Even though we’ve observed [Miguel] Andujar with a Barrel rate of 25 percent, no player with at least 650 PA in a season has recorded a single-season Barrel rate higher than 12.8 percent (Judge, 2017). Over a three-year period of at least 1,800 PA, the highest observed Barrel rate rate belongs to Nelson Cruz at 9.6 percent.

These facts mean Andujar is unlikely to sustain a 25 percent rate for 650 PA and even less likely to sustain it for 1,800. Despite observing his on-field Barrel rate of 25 percent, we should be confident his true-talent rate is lower.

How do you compare players with different amounts of playing time to each other? How do you account for the rarity of a feat when analyzing a player’s on-field accomplishments? How do you estimate a player’s true talent based on what he did on the field?

Read on for my answer.