Correlating Rookie and Short-A walk and strikeout rates to the Major Leagues

Introduction

As I began my series of correlating prospect walk and strike ratios to future hitting success, a question arose from Carson Cistulli. How do minor and major league walk and strikeout rates compare to each other? I did a little of this analysis in my original series at The Platoon Advantage, but never pursued it in any depth. Consider this a supplement to the already running series.

Method

Success rates for Short-season A League prospects based on walk and strikeout rates

Using historical prospect lists, which current prospects have helped their chances at Major League success based on their walks, strikeouts, and age?

I took the same data but instead split minor league seasons into various BB% or K% bins, basically the equivalent of Very Low, Low, Average, High, and Very High. Then I compared those rates with the player’s eventual MLB rate. If a player had fewer than 500 MLB PAs, I did not count his rate, since that is too small of a sample.

Hopefully the following tables are simple to understand, but just in case I didn’t design them well enough, I will explain. The first column contains the labels for BB% or K% at the minor league level. The third through eighth columns are the percentage of prospects that had that column heading’s major league BB% or K%. This means that rows add up to 100%, but columns do not.

Walk Percentage

Strangely, the amount of prospects without a full season of MLB experience rises with walk rate. This is a low-level phenomenon and does not occur in the higher reaches of the minor leagues. Of the prospects that reach the majors, their walk rate either holds steady or drops. There are very few instances where a player increases his walk rate, though it does happen often enough.

Strikeout Percentage

Prospects tend to strikeout more often in the majors than in the minors. That’s not exactly ground-breaking stuff, but the actual percentages are what are most interesting here.

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Statistics courtesy of Fangraphs and Baseball Prospectus.

Chris St. John is a writer at Beyond The Box Score. You can follow him on Twitter at @stealofhome.

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