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

By Chris St. John


Introduction
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.

Method
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.

History
Rookie and Low-A
Single-A
Advanced-A
Double-A

Triple-A
389 of the 480 prospects in this dataset accumulated at least 150 plate appearances in Triple-A. 19% were successful, 20% were average and 61% were busts. This is close to the overall 21/21/58 trend for all prospects.

Walks

58 prospects had below average walk rates in Triple-A and only seven of them turned into productive hitters (Juan Gonzalez, Magglio Ordonez, Alfonso Soriano, Raul Mondesi, Javy Lopez, Eric Chavez, Glenallen Hill). The two prospects with very low walk rates were Aaron Hill and Matt Moses. Hill has been an serviceable second baseman thus far in his career, but his value (apart from 2009) has not been in his bat.

42% of the players with higher than average Triple-A walk rates become productive hitters. Only 38% were busts. That is the best percentage of this entire series. Three players with very high Triple-A walk rates were busts: Cliff Pennington, Kerwin Moore and Willie Ansley. Pennington, like Hill, is not a typical bust. Both his total PA and Batting Runs/PA fall just short of the Average/Bust cutoff.

Correlation to MLB
This graph shows the correlation between Triple-A and MLB walk rates.

Click to enlarge

2007-2012 Prospects
High Walk Rate: Austin Jackson, Brandon Belt, Kyle Blanks, Carlos Santana, Justin Smoak, Alex Gordon, Evan Longoria, Billy Butler, Kurt Suzuki, Daric Barton, Brandon Allen
Low Walk Rate: Erick Aybar, Tyler Colvin, Delmon Young, Chin-Lung Hu, Wilson Ramos, Brent Morel, Chris Heisey, Eduardo Escobar, Thomas Neal, Jose Iglesias


Strikeouts

After rising at each successive level (7.5%, 14%, 20%), the amount of productive hitters with high strikeout rates fell to 16% in Triple-A. The lone productive hitter with a very high Triple-A strikeout rate was Russell Branyan. Just 18% of the hitters with low strikeout rates were productive, leaving the average category as the best option.

2007-2012 Prospects
High Strikeout Rate: Sean Rodriguez, Greg Halman, Taylor Teagarden, Austin Jackson, Brett Jackson, Trayvon Robinson, Tyler Flowers, Fernando Perez, Chris Heisey, Pedro Alvarez, Tyler Colvin
Low Strikeout Rate: Jacoby Ellsbury, Miguel Montero, David Cooper, Angel Salome, Michael Brantley, Billy Butler, Alberto Callaspo, Carlos Gonzalez, Andy LaRoche, Kevin Kouzmanoff, Julio Borbon

Correlation to MLB
This graph shows the correlation between Triple-A and MLB strikeout rates.

Click to enlarge

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

Click to Enlarge

Conclusion
Walk and strikeout rates are most closely correlated between Triple-A and the Major Leagues (surprise!). The best harbinger for a prospect’s success is a high walk rate in Triple-A. High strikeout players in Triple-A don’t pan out as well as those in Double-A. I’ll finish this series with a wrap-up post and hopefully dig a little deeper into finding out what makes a productive hitting prospect.

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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