Pittsburgh Pirates: Top Performing Minor League Hitters Part One

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Pittsburgh Pirates
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Looking at how the Pittsburgh Pirates prospect hitters in the minor leagues performed in 2018 and who to keep an eye out for in 2019 using z-scores in several offensive categories.

In this month to date, Nick has released our site’s top 30 prospects and earlier in the offseason, I’ve documented composite top 100 rankings based on four major prospect sites.  Today will be the first part of a four-part series, looking at how the Pittsburgh Pirates prospect hitters performed in 2018 to look to see who might be an underrated prospect; the series will go in the order of the really low minors (the three rookie leagues), the low minors (A ball), the upper minors (Double-A and Triple-A), and then ending with a wrap up.

Often times the phrase “you can’t scout the stat line” is thrown around, and it is true, there’s more variables in terms of makeup, a pitcher’s stuff, a hitter’s approach, base running, and fielding, etc.  Teams do try to use a model, with Chris Mitchell’s KATOH being one of the more popular ones, and Kevin Creagh developed the Stat Scout Line.  This analysis isn’t a model, rather a summation of z-scores in different statistics to determine which hitters have performed well compared to other prospects.

Because each level of the minor leagues has different players and the goal is to look at potential prospects (sorry Ryan Lavarnway), setting a maximum age requirement and minimum plate appearance requirement is a must.  Since this is looking at 2018, there will be some players who appear on these lists that are no longer in the organization because of a trade, free agency, or they were released.  For each level among hitters we have the following requirements and the total number of player seasons:

Minor League Level Sample Requirements
Level Max Age Min PA Player Seasons
R (Dominican) 19 200 237
R (GCL) 19 50 137
R (Appy) 21 50 128
A- (New York Penn) 22 50 205
A (South Atlantic) 22 50 188
A+ (FSL) 23 100 154
AA (Eastern) 24 100 117
AAA (International) 25 100 108

Across each level, the statistics used for how well a prospect has performed will be the following: age, average, on-base, slugging, isolated power (ISO), strikeout rate, and unintentional walk rate.  Strikeout rate will be multiplied by negative one as a lower than average rate is better, and the same goes for age; a prospect younger than average and performing deserves more credit.  The averages for each level are:

Minor League Level Averages
R (Dominican League) 17.5 241 0.254 0.352 0.357 0.103 19.4% 11.1%
R (GCL) 18.2 126 0.246 0.320 0.349 0.102 23.0% 8.1%
R (Appy) 19.9 156 0.263 0.349 0.396 0.134 22.2% 10.2%
A- (New York Penn) 20.7 159 0.241 0.319 0.348 0.107 22.4% 8.7%
A (South Atlantic) 20.8 269 0.248 0.312 0.380 0.132 23.5% 7.3%
A+ (FSL) 21.8 279 0.254 0.323 0.371 0.118 21.2% 8.1%
AA (Eastern) 22.9 138 0.256 0.329 0.396 0.140 21.1% 8.9%
AAA (International) 23.7 125 0.260 0.327 0.404 0.144 21.7% 8.0%