Success rates for Rookie League prospects based on walk and strikeout rates

Introduction

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?

Method

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 lie in terms of BB% and K% values. These numbers vary by league and year, but these are good benchmarks on average.

	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.

Results

Here are the historical results for prospects at the Rookie level, split by BB%, K%, and age.

The sample sizes are not big, but there are a few interesting trends to note. First, most prospects have low or average K rates. 47 appear in the low K categories, while only 17 have a high amount. Also, the top categories for productive% are at the extremes – High/High and Low/Low. High/Low, which may be considered the best category, has the lowest success rate. Only one of the 15 prospects with those ratios went on to provide a lot of offense in the major leagues. Any guesses as to who this was? It was Prince Fielder in 2002.

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

20 is the magical age for Rookie ball. Anything older than that and you should at least be in short season A, if not low-A or High-A.

2013 Top Prospects

How do 2013 preseason consensus top 190 prospects and early draft picks that played in Rookie ball this year stack up in this analysis?

Name	Team	BB+	SO+	Prod%	Avg%	Bust%
Travis Demeritte	Rangers	174	141	43%	0%	57%
Drew Ward	Nationals	132	112	34%	6%	60%
Austin Meadows	Pirates	134	112	34%	6%	60%
Reese McGuire	Pirates	80	46	31%	19%	50%
Cord Sandberg	Phillies	129	93	25%	13%	63%
Riley Unroe	Rays	172	108	25%	13%	63%
Gosuke Katoh	Yankees	132	103	25%	13%	63%
Dominic Smith	Mets	130	94	25%	13%	63%
Dom Nunez	Rockies	87	79	22%	22%	56%
Billy McKinney	Athletics	87	71	22%	22%	56%
Tucker Neuhaus	Brewers	111	129	21%	13%	66%
Ivan Wilson	Mets	118	179	21%	13%	66%
Ryan McMahon	Rockies	117	119	21%	6%	73%
Thomas Milone	Rays	48	125	20%	20%	60%
Kevin Franklin	Reds	70	137	20%	20%	60%
Nick Ciuffo	Rays	56	120	16%	21%	63%
D.J. Davis	Blue Jays	106	149	13%	0%	88%
Christian Arroyo	Giants	96	77	13%	25%	63%
Justin Williams	Diamondbacks	52	110	11%	22%	67%
Dustin Peterson	Padres	55	97	11%	22%	67%
J.P. Crawford	Phillies	157	75	10%	10%	80%
Ryder Jones	Giants	89	116	6%	24%	71%
Clint Frazier	Indians	91	157	0%	25%	75%
Hunter Dozier	Royals	143	63	0%	20%	80%
Oscar Mercado	Cardinals	100	107	0%	11%	89%
Stryker Trahan	Diamondbacks	96	110	0%	11%	89%
Daniel Palka	Diamondbacks	127	94	0%	0%	100%

Travis Demeritte was one of the Rangers 2013 1^st round picks. He had extremely high walk and strikeout rates, accounting for 45% of his PAs this year. That is not a bad thing this year, but he will need to cut down on the strikeouts if he graduates to low-A next year.

The Pirates have a lot to look forward to in the minor leagues, and Meadows and McGuire are just increasing the franchise’s outlook.

Things don’t look very good for the guys at the bottom of the chart, but their careers are just beginning. Both Dozier and Palka are a little old for Rookie ball but their ratios don’t look bad otherwise. The biggest red flag (no pun intended) is with Clint Frazier. A 31% K rate is extremely high, reminiscent of Joel Guzman in 2002. Assuming he moves up to low-A in 2014, he will need to both drop his K rate and increase his BB rate to help his chances.

Just two top 190 hitters qualified as here this year and neither rank favorably. Trahan (#129 on the preseason list) is in the bottom five, but the Blue Jays’ D.J. Davis (#138) may have hurt his chances even more, since he is older and had a much higher K rate.

Conclusion

Players who are 21 or older in rookie ball are behind in their development. Historically, the most productive hitters to come out of this level are at the extremes in their approach – either they walk and strike out a lot or don’t do much of either. Oddly enough, the players who are just average at those things have not gone on to have much success in the major leagues.

As with any statistical analysis of minor league players, everything must be viewed in context and compared with scouting reports. However, this should create a basis for conversation on some players. Which other players in Rookie ball 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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