Tuesday, March 6, 2012

What Do Minor League Walk and Strikeout Rates Tell Us About Prospects? Double-A Edition

By Chris St. John

A few months ago, I created a database that includes all of the prospect rankings from Baseball America, Keith Law and Kevin Goldstein. I didn't have a direct purpose for it, I'm just the type of person who likes to accumulate as much data as possible. So it sat around on my computer until I found a good use for it. Well, thanks to fantasy baseball and Starling Marte's horrible 3.8% walk rate in AA last season, I have. Marte is a possible target in my dynasty minor league draft and I wanted to see what other prospects had poor walk rates and how successful they were in their careers.

In interest of saving digital space (and your scrolling finger), I will only post the full method on the Rookie and Low-A edition of this series.

Rookie and Low-A

434 of the 480 prospects in this dataset accumulated at least 150 plate appearances in Double-A. 20% were successful, 20% were average and 60% were busts. This is close to the overall 21/21/58 trend for all prospects.

Only eight of 66 prospects (12%) with low or very low walk rates turned into productive MLB hitters (Corey Hart, Raul Mondesi, Chipper Jones, Juan Gonzalez, Carlos Lee, Jose Reyes, Richard Hidalgo, Javy Lopez). 21 of the 62 prospects with high or very high walk rates (34%) became productive. Only two prospects with very high walk rates were busts (Joe Lawrence, Kerwin Moore).

Correlation to MLB
This graph shows the correlation between Double-A walk rates and MLB walk rates.
Click to enlarge

2007-2012 Prospects
High Walk Rate: Derek Norris, Cameron Maybin, Logan Morrison, Tyler Flowers, Dexter Fowler, Nick Weglarz, Jaff Decker, Justin Smoak, Lou Marson
Low Walk Rate: Hector Gomez, Julio Borbon, J.P. Arencibia, Wilson Ramos, Jose Iglesias, Engel Beltre, Brett Lawrie, Angel Salome, Starling Marte, Carlos Triunfel


The amount of productive hitters with high strikeout rates continues to rise. In Single-A, it was 7.5%. In Advanced-A, it was 14%. Now in Double-A, it is 20% - right in line with the overall total. However, 25% of players with below average strikeout rates became productive. It's still better to have a low strikeout rate, but it's not necessarily bad to have a high one.

2007-2012 Prospects
High Strikeout Rate: Kyle Skipworth, Taylor Teagarden, Greg Halman, Angel Salome, Matt Sweeney, Michael Saunders, Brandon Wood, Ike Davis, Derek Norris, Travis Snider
Low Strikeout Rate: Alberto Callaspo, Jacoby Ellsbury, Jed Lowrie, Cedric Hunter, Michael Brantley, Erick Aybar, Christian Colon, Starlin Castro, Ben Revere, Chin-Lung Hu

Correlation to MLB
This graph shows the correlation between Double-A strikeout rates and MLB strikeout rates.
Click to enlarge

Strikeout to Walk Ratio
Finally, this plot shows the relationship between Double-A K/BB and Major League Batting Runs per Plate Appearance:
Click to Enlarge

The correlation coefficients for walks and strikeouts continue to rise, with strikeout rates still a step ahead of walk rates. Productive hitters haven't improved upon their Double-A strikeout rates as much as they have their walk rates. In order to be a productive hitter, one must achieve a major league walk rate better than expected. This still doesn't guarantee productivity, but it does increase the chances greatly.

If you would like to know anything specific about the data, you can contact me in the comments section below or on Twitter @stealofhome.

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