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Success rates for Single-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?



This is the third and final time I will look at historical walk and strikeout rates for prospects. If you followed my previous installments, much of this will look familiar to you; however, the results are more complex and different. For those who are new, the basic premise is this: how likely is it that an offensive prospect succeeds in the major leagues based only on his minor league walk and strikeout rates?

Previous Levels: Rookie | Short-A


First, I compiled the minor league numbers for all Baseball America top 100 offensive prospects from 1990 to 2007. I stopped at this year to allow enough time for the player to achieve MLB success. I only include top 100 prospects to add in a form of scouting to the picture. Stats and scouting should work hand-in-hand and an analysis similar to this can help augment a scout’s evaluation of talent. Next, I compared each prospect’s walk and strikeout rate to the league average that year, creating BB+ and K+ metrics. Finally, I compared the walk and strikeout rates at various ages and levels of prospects in the minor leagues to their career MLB Fangraphs Batting runs.

In order to put players into the low, average, and high categories for BBs and Ks, I use a 15% variation from 100 BB+ or K+. This means that 85-115 marks average for each, while players below 85 are "Low" and players above 115 are "High." Since this analysis relies on bins, I allow for a 5% variation on the cutoffs. For instance, if a player has an 83 BB+ (78-88), I look at the historical percentages for both low and average walk rates.

Prospects are required to have 150 PAs at a level to qualify in this analysis.

The following table is an estimate of where these cutoffs actually lie in terms of BB% and K% values.

BB% K%
Low 7.7% 15.4%
High 10.5% 20.8%

A player with at least 0.01 Batting runs in 1500 career plate appearances is tagged "Productive," while players with negative batting runs or fewer than 1500 career PAs are "Busts." It is important to note that I am only interested in hitting ability. This is how Edgar Renteria ends up in the "Bust" category. He had a great career, accumulating 35.7 fWAR; however, his batting was worth -52.3 runs.


Here are the historical results for prospects in short season A, split by BB%, K%, and age.


The success rates for the different categories are similar here to the Rookie level. High/High players have the best chance, while the players in trouble tend to gather towards average.

Here is an overall success table for this level, based solely on age.


Teams seem to send drafted college players to short-season A, hence the large number of 21-year olds. Once a player is in his age-22 season, he should be ready for the next level.

Prospects in 2013

How do 2013 preseasons consensus top 190 prospects and early draft picks that played in single-A this year stack up in this analysis?

Name Team BB+ SO+ Prod% Avg% Bust%
Jeimer Candelario Cubs 135 75 42% 8% 50%
Jesse Winker Reds 147 76 42% 8% 50%
Albert Almora Cubs 71 54 35% 12% 53%
Jose Peraza Braves 77 62 35% 12% 53%
Byron Buxton Twins 156 85 34% 10% 56%
Carlos Correa Astros 127 78 33% 0% 67%
Adalberto Mondesi Royals 72 108 33% 0% 67%
Jacob May White Sox 79 92 33% 0% 67%
Adam Walker Twins 64 102 33% 0% 67%
Devon Travis Tigers 117 46 33% 4% 63%
Jorge Polanco Twins 91 55 30% 20% 50%
Patrick Wisdom Cardinals 113 132 30% 10% 60%
Dan Vogelbach Cubs 130 74 27% 18% 55%
Mookie Betts Red Sox 194 58 27% 18% 55%
Kevin Plawecki Mets 93 56 27% 0% 73%
Corey Seager Dodgers 124 91 27% 12% 62%
Rio Ruiz Astros 121 95 27% 12% 62%
Colin Moran Marlins 98 70 25% 17% 58%
Brandon Drury Diamondbacks 92 77 25% 17% 58%
Dorssys Paulino Indians 65 85 24% 25% 51%
Rosell Herrera Rockies 127 86 20% 9% 71%
Josh Bell Pirates 114 85 18% 11% 71%
Tim Anderson White Sox 87 127 18% 8% 73%
Max Kepler Twins 104 80 17% 13% 70%
Carlos Tocci Phillies 55 82 17% 50% 33%
Bubba Starling Royals 121 126 17% 17% 67%
Jorge Alfaro Rangers 76 129 17% 17% 67%
Patrick Kivlehan Mariners 78 83 17% 10% 73%
Gregory Bird Yankees 212 113 15% 8% 77%
Barrett Barnes Pirates 94 114 14% 7% 79%
Lewis Brinson Rangers 109 186 11% 11% 78%
Roman Quinn Phillies 103 105 9% 9% 82%
Nick Williams Rangers 42 133 0% 15% 85%
Joey Gallo Rangers 122 181 0% 0% 100%
Victor Roache Brewers 101 130 0% 0% 100%
Brandon Dixon Dodgers 55 140 0% 0% 100%
Nomar Mazara Rangers 99 127 0% 0% 100%

At the top of the list are two lesser prospects than some of the heavy hitters in this level. Look for both Candelario and Winker to be promoted to at least advanced-A next season and move up prospect lists as well. After those two, we find some elite and well-known guys, including Buxton, the top prospect in baseball. He spent enough time in advanced-A to be considered for that list, and actually improved his stock more at that level. Almora and Correa are right there with him, along with Peraza, Baseball America’s #16 prospect in the South Atlantic League.

Mondesi appears near the top of the list on the strength of his age. As he starts moving up the ladder, he will need to start walking more often, and that may come with maturity as a hitter. However, his strikeouts don’t pose a threat thus far in his career. There have been very few 18 year-old prospects above single-A, so I don’t envision the Royals promoting him until 2015, but if he continues to grow and mature, it is possible he reaches high-A at the end of next season.

At the bottom of the chart are the Rangers prospects. They have a lot of all-or-nothing power hitters who are providing more nothing than all. The only productive hitters with similar rates in single-A were Russell Branyan, Mike Cameron, Preston Wilson, Austin Kearns, and Josh Phelps. Cameron and Wilson had more speed than the Rangers quintuplets, while Kearns and Phelps only had a few productive seasons. Branyan represents the ceiling of these guys offensively if they don’t stop striking out so much.


Single-A is the place where prospects start honing their approach. Those who are able to do so get the call up to better and more advanced leagues, while those who don’t start to flame out quickly. Extreme approaches are no longer rewarded but instead a good mix of walking more than striking out.

Which other players in single-A caught your eye this year?

. . .

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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