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JAVIER: Analyzing prospects by minor league career

Third in a three-part series on prospect analysis, which contains an interactive visualization to find what a hitter's statistics in the minor leagues tell us about his probability of success in the majors.

Joe Camporeale-USA TODAY Sports


This is the third and final post in my reveal of the JAVIER system, this one covering analysis for a prospect based on his entire minor league career. Read the introduction post for a full description of the method and an application to some of the current prospects. This particular visualization will be effective for finding how much a prospect is hurting or helping his status based on his production over a large number of years. Age and level are not a consideration here, each player is compared on their overall stats.

The following are the definitions for Productive, Average, and Busted hitters. There are a few necessities for a player to qualify for any of the categories. They must be a non-pitcher, have played a majority of their career after 1978, have had an MLB debut prior to 2010, or were in the minor leagues in 2008 and were 25 in 2013. The final criteria find those older players who never made the major leagues.

Productive: At least 1,000 PA in the majors and at least .0275 VORP per PA. The range of these 508 hitters goes from Matt Murton (29.3 VORP in 1,058 PA) to Barry Bonds (1,592.7 VORP in 12,606 PA)

Average: At least 1,000 PA in the majors and between -.025 and .0275 VORP per PA. The range of these 649 hitters goes from Rafael Belliard (-63.3 VORP in 2,524 PA) to Omar Vizquel (296 VORP in 12,013 PA).

Bust: Fewer than 1,000 PA in the majors or less than -.025 VORP per PA. There are 12,627 busts, 11,038 of which never made the major leagues (yeah). The hitter with the most VORP who is labeled a "Bust" is Troy Neel (42.9 VORP in 861 PA), a former first baseman for the Athletics (and child support payment evader).

Average percentages

This table gives the average productive, average, and bust percentages by career. This will be useful to compare to the results in the visualization.


Finding the z-scores

The visualization requires the input of z-scores. These can be estimated, but I have provided a document for more accurate calculations. The actual z-scores themselves are based on the average and standard deviation of all minor league hitters over those years.

Input the first and last year the prospect was in the minor leagues (2013 is the maximum) and the appropriate statistics.

Next to zBB, zK, and zISO are inputs for the range you would like to use on each z-score. The default is plus or minus one, but this can be changed if you need a smaller or larger range. This depends on the amount of similar seasons you find in the visualization.


Finally, the fun stuff. Here you will be able to turn a player's PA, AB, 2B, 3B, HR, BB, and K totals into a percentage of success or failure.

Instructions for the visualization

Use the z-scores calculated above to set a range on the zBB, zK, and zISO filters. The upper left hand corner of the viz gives the outputs you desire, in both total and percent form. These boxes tell you what percentage of players who had a similar minor league career went on to be a productive, average or busted player. If the total amount of similar players is fewer than 20 to 30, increase the slider ranges a bit.

The chart at the bottom of the visualization shows where those comparable seasons lie in terms of their zBB-zK and zISO. The size of the bubble gives the amount of MLB PAs and the color gives the total MLB VORP. Hover over each point to find information about that player.

If you are simply interested in finding percentages for a large group of players and don’t need to use the visualization, I have included a spreadsheet to help facilitate that. Make sure you fill in all light blue cells and copy and paste using keyboard shortcuts Ctrl+C/Cmd+C and Ctrl+V/Cmd+V for all cells for each line you have data. The maximum "To" year is 2013.

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Statistics courtesy of Baseball Prospectus.

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