Minors to the Majors: MiLB Batted Ball Baselines & Leaders

 Note: Do to a calculation error involving popups, the values initially report were off by a small bit. Everything is corrected now.

Our Dark Overlord continues to install enhancements to FanGraphs. One item which he has sneaked in over the weekend in Swinging Strike (must add to custom dashboard) and Groundball Rates for minor league pitchers (example). With the data now available to query, it’s time to find the league specific baselines and compare some highly touted prospects. Today, I will just concentrate just on the batted ball data.

Anytime new data becomes available, the baselines values are the starting point for an analysis so comparisons can be made. First, here are the overall league ground ball rates from 2016.

MiLB Batted Ball Averages
Level GB% LD% FB% PU%
MLB 44.7% 20.7% 34.6% 3.4%
AAA 44.9% 20.6% 34.6% 7.3%
AA 45.4% 20.1% 34.5% 7.3%
A+ 45.5% 19.8% 34.7% 7.5%
A 46.0% 19.3% 34.7% 7.5%
A- 47.9% 18.8% 33.3% 7.8%
Rookie 47.9% 20.8% 31.3% 8.6%

There is some funkiness going on in Rookie Ball and the Majors but the general trend is for ground ball rates to drop as the level approached the majors. Generally, the numbers are steady. With the league averages out of the way, I will move onto pitchers.

Pitchers

For pitchers, I will use a starting pitcher baseline. Combining starters and relievers causes a mess. Additionally, the pitchers who fantasy owners care about in the minors are normally the starters.

For pitchers, I consistently use ground-ball rate to describe a pitcher’s batted ball profile. It allows owners to understand the good and bad values for just one metric. To get the average starter values, I compared players from 2014 to 2016 in which they started at least half their games and pitched a minimum of 40 innings. I found the median value and set it to a 50 (Average) value. Then I found the standard deviation and added it to the median value, and graded it 60. I continued the standard deviation addition to an 80 grade. Finally, I subtracted the standard deviation value from the median to create the below average grades. Here are the results.

MiLB Pitcher GB% Grades
Grade Description AAA AA A+ A A- Rookie
80 Outstanding 65.0% 66.5% 66.8% 66.6% 68.6% 69.1%
70 Very Good 58.0% 59.2% 59.6% 59.6% 61.5% 62.1%
60 Above Average 51.0% 51.9% 52.4% 52.6% 54.5% 55.0%
50 Average 44.0% 44.5% 45.3% 45.6% 47.4% 48.0%
40 Below Average 37.0% 37.2% 38.1% 38.6% 40.3% 40.9%
30 Well Below Average 29.9% 29.9% 30.9% 31.6% 33.2% 33.8%
20 Poor 22.9% 22.5% 23.7% 24.6% 26.1% 26.8%

Remember, this grade just informs us on how the pitcher performs compared to the rest of the league on groundballs. Being an extreme flyball pitcher also has an advantage. From some of my historical work, pitchers start seeing an ERA below their ERA estimators with a 70 grade or higher or a grade under 30.

Besides the groundball numbers, I decided to run the Popup% (FB%*IFFB%) for a reference.

MiLB Pitcher Popup% Grades
Grade Description AAA AA A+ A A- Rookie
80 Outstanding 15.4% 15.8% 15.1% 15.3% 16.7% 18.5%
70 Very Good 12.6% 12.9% 12.4% 12.7% 13.6% 15.1%
60 Above Average 9.8% 10.1% 9.7% 10.0% 10.6% 11.6%
50 Average 7.0% 7.2% 7.1% 7.3% 7.5% 8.2%
40 Below Average 4.1% 4.3% 4.4% 4.6% 4.4% 4.8%
30 Well Below Average 1.3% 1.5% 1.7% 2.0% 1.4% 1.3%
20 Poor -1.5% -1.4% -1.0% -0.7% -1.7% -2.1%

A high popup rate may be a sign of a why a pitcher may be over-performing at a certain level.

With the overall values known, here are the pitchers on Baseball America’s top 100 prospect list. I found their combined 2016 and 2017 groundball and popup rates since the 2017 season is just starting.

GB% and Popup% For Pitchers in BA’s Top 100
Name GB% Popup%
James Kaprielian 66.7% 8.3%
Riley Pint 57.3% 6.5%
Sixto Sanchez 56.4% 6.1%
Ian Anderson 55.2% 6.9%
Jason Groome 54.6% 4.6%
Yadier Alvarez 53.1% 4.8%
Dylan Cease 52.0% 2.9%
Lucas Giolito 51.5% 3.9%
Mike Soroka 51.3% 6.3%
Cody Reed 50.7% 5.8%
Erick Fedde 49.6% 6.0%
Brandon Woodruff 49.5% 8.1%
Sean Reid-Foley 49.2% 6.8%
Tyler Beede 48.1% 7.1%
Amir Garrett 47.6% 8.8%
German Marquez 47.2% 7.2%
Mitch Keller 46.7% 7.2%
Anderson Espinoza 46.5% 8.2%
A.J. Puk 46.2% 8.8%
Anthony Banda 45.9% 6.8%
Justus Sheffield 44.9% 8.3%
Justin Dunn 44.8% 4.8%
Cal Quantrill 44.6% 4.1%
David Paulino 44.1% 9.5%
Francis Martes 43.5% 7.1%
Jeff Hoffman 43.2% 4.2%
Luis Ortiz 43.2% 8.1%
Stephen Gonsalves 42.4% 12.8%
Sean Newcomb 42.3% 8.1%
Tyler Glasnow 41.8% 12.1%
Michael Kopech 41.1% 15.2%
Kolby Allard 41.0% 7.5%
Jharel Cotton 40.8% 10.2%
Alex Reyes 39.2% 12.4%
Triston Mckenzie 38.6% 12.5%
Josh Hader 38.2% 9.9%
Luke Weaver 38.0% 11.3%
Franklin Perez 36.9% 10.6%
Reynaldo Lopez 35.8% 9.0%
Matt Manning 34.9% 11.6%
Jose De Leon 34.5% 10.8%
Brent Honeywell 31.0% 13.3%

On average, these pitchers have an above average groundball rate. The one pitcher who stood out to me was Riley Pint. He’s known for 100 mph fastball but not his groundball rates. If it stays near 60%, he could be elite, even in Colorado.

With the pitchers done, time to move onto the hitters.

Hitters

I followed the same procedure for hitters as I did with pitchers by putting the hitter’s ground ball tendencies on a 20-80 scale (min 40 PA, 2014-2016). Normally, hitter groundball rates aren’t used but I find them extremely helpful to determine a hitter’s swing path. A high ground ball rate means a slugger will probably need to rework his swing for line drives as he gets closer to the majors.

MiLB Batter GB% Grades
Grade Description AAA AA A+ A A- Rookie
80 Outstanding 68.4% 68.4% 70.5% 71.6% 75.8% 74.5%
70 Very Good 60.4% 60.6% 62.3% 63.1% 66.6% 65.5%
60 Above Average 52.3% 52.7% 54.1% 54.7% 57.4% 56.4%
50 Average 44.3% 44.9% 46.0% 46.3% 48.2% 47.4%
40 Below Average 36.2% 37.0% 37.8% 37.9% 39.0% 38.3%
30 Well Below Average 28.2% 29.2% 29.6% 29.4% 29.8% 29.3%
20 Poor 20.1% 21.4% 21.4% 21.0% 20.6% 20.2%

The one item to notice with hitters, the deviation from average is a bit more than that of pitchers.

Besides the groundball rate, I have also created the same information for line drives for reference.

MiLB Batter LD% Grades
Grade Description AAA AA A+ A A- Rookie
80 Outstanding 34.2% 33.3% 31.6% 31.8% 33.0% 34.2%
70 Very Good 29.6% 28.5% 26.8% 27.2% 28.0% 28.2%
60 Above Average 25.0% 23.8% 21.9% 22.6% 23.1% 22.2%
50 Average 20.4% 19.1% 17.1% 18.0% 18.1% 16.2%
40 Below Average 15.8% 14.4% 12.2% 13.4% 13.1% 10.2%
30 Well Below Average 11.2% 9.7% 7.4% 8.8% 8.2% 4.2%
20 Poor 6.6% 5.0% 2.5% 4.2% 3.2% -1.8%

It’s not a surprise to see line drive rates increase as hitters gain strength and get closer to the majors.

Now that the averages are known, here are how hitters in Baseball America’ top 100 rank according to their groundball rate.

GB% and LD% For Batters in BA’s Top 100
Name GB% LD%
Blake Rutherford 59.3% 17.7%
Ronald Acuna 54.6% 19.2%
Mickey Moniak 54.6% 17.9%
Raimel Tapia 53.8% 17.7%
Kevin Newman 53.5% 19.5%
Nick Gordon 51.5% 20.9%
Amed Rosario 50.1% 21.5%
Leody Taveras 49.7% 17.7%
Kyle Lewis 49.5% 14.3%
Jorge Alfaro 48.6% 22.0%
Delvin Perez 48.1% 17.6%
Ozzie Albies 46.9% 20.6%
Chance Sisco 46.2% 27.6%
Victor Robles 45.9% 17.7%
Manuel Margot 45.9% 24.2%
Gleyber Torres 45.9% 22.6%
Josh Bell 45.8% 22.6%
Rafael Devers 45.7% 23.3%
Alex Verdugo 45.5% 22.4%
Anthony Alford 45.3% 24.5%
Corey Ray 45.0% 23.0%
Bradley Zimmer 45.0% 23.3%
Albert Almora Jr. 44.3% 27.1%
Lewis Brinson 44.2% 16.3%
Franklin Barreto 43.6% 22.1%
Yoan Moncada 43.2% 27.3%
Carson Kelly 43.0% 25.5%
Clint Frazier 42.9% 23.0%
Brendan Rodgers 42.8% 23.3%
Francisco Mejia 42.7% 23.7%
Eloy Jimenez 42.5% 21.5%
Ian Happ 42.5% 21.5%
Dominic Smith 42.4% 23.8%
J.P. Crawford 41.4% 19.9%
Dansby Swanson 41.1% 23.2%
Kyle Tucker 41.0% 25.6%
Willy Adames 40.7% 25.0%
Willie Calhoun 40.7% 20.1%
Rowdy Tellez 40.5% 20.5%
Jake Bauers 39.9% 22.3%
Casey Gillaspie 39.8% 25.0%
Jorge Mateo 39.0% 16.8%
Nick Senzel 39.0% 21.2%
Vladimir Guerrero Jr. 38.9% 20.1%
Austin Meadows 38.8% 20.5%
Hunter Renfroe 36.9% 19.3%
Zack Collins 36.6% 15.2%
Isan Diaz 36.0% 18.8%
Tyler O’Neill 35.9% 18.2%
AJ Reed 33.0% 25.2%
Andrew Benintendi 32.7% 22.7%
Aaron Judge 32.1% 25.0%
Cody Bellinger 30.4% 21.4%
Matt Chapman 29.8% 21.4%

Two names stick out to me, Mickey Moniak and Raimel Tapia. Both have GB% grades near 65. Not good.

The one issue I have with Moniak is that his bat control is too good and he’s developed some bad habits. He is used to swinging at and hitting everything (see Javier Baez). As the pitchers get better, he’s going to have more and more plate discipline issues. Additionally, he may still make contact out of the strike zone and just generate weak contact. He needs to show that he can adjust and grow as a hitter.

Tapia seems like a poor man’s DJ LeMahieu but without the walks and power and a little more speed. Tapia will be a high contact Colorado hitter and these individuals post decent batting averages. Tapia problem is one I have been bringing up recently with hitting prospects, the focus on batting average when discussing a the hit tool. Tapia has a 60-grade hit tool (FanGraphs, Baseball America, and MLB.com) but doesn’t have a good approach at the plate. He has swung at pitches out-of-the-zone 47% of the time in the majors (30% is league average). Plate discipline needs to be a component to the Hit tool.

That’s it for today. Lots of new data to help answer some age-old questions. I’ve gone over some of the minor league batted ball baselines and will continue the research.Until then, happy prospecting.





Jeff, one of the authors of the fantasy baseball guide,The Process, writes for RotoGraphs, The Hardball Times, Rotowire, Baseball America, and BaseballHQ. He has been nominated for two SABR Analytics Research Award for Contemporary Analysis and won it in 2013 in tandem with Bill Petti. He has won four FSWA Awards including on for his Mining the News series. He's won Tout Wars three times, LABR once, and got his first NFBC Main Event win in 2021. Follow him on Twitter @jeffwzimmerman.

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MeDeke
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MeDeke

Overall, I love this – well done, Jeff!

One minor note: “Plate discipline needs to be a component to the Hit tool.”

I’d prefer to see a separate Plate Discipline tool as opposed to lumping it in to the Hit tool. Just a personal preference, but this could be very helpful for identifying players who eventually end up following the 3 True Outcomes path – one can have a mediocre hit tool but if they have plus raw power and plus plate discipline, they can be an average or better hitter.