Fantasy: Estimated Barrels For Minor League Hitters

Image credit: (Photo by Bill Mitchell)

The MLB Statcast metric “barrels” has quickly become the standard by which analysts gauge players’ power. Knowing how frequently a major league hitter makes ideal contact to do damage, as measured by exit velocity and launch angle of batted balls, tells us a lot about what type of power production can be expected.

For years, major league organizations have had the tools to develop advanced proprietary metrics based on batted-ball data, including barrels-style metrics for minor league hitters. Because that information is not publicly available, I developed the next-best thing: estimated barrels for minor league hitters.

Estimated barrels allows fantasy managers to project power performance from prospects and thus generate leads for possible dynasty targets. In 2019, the most recent minor league season for which we have data, Yordan Alvarez, Trent Grisham, Jazz Chisholm and Dylan Carlson were among the breakout prospects for whom estimated barrels was bullish.

What Is A Barrel (And Why Should I Care)?

Major League Baseball data guru Tom Tango created the barrels metric late in the 2016 season. Statcast had been unveiled to the public only a year before. A barrel is a batted ball with a pairing of exit velocity and launch angle that has historically resulted in a batting average greater than .500 and a slugging average greater than 1.500.

For perspective, the top 10 qualified major league hitters in terms of barrels per batted ball in 2020 were the types of players one might expect: Miguel Sano, Fernando Tatis Jr., Juan Soto, Teoscar Hernandez, Brandon Lowe, Bryce Harper, Eloy Jimenez, Ronald Acuña Jr., Nick Castellanos and Corey Seager.

What Is An Estimated Barrel (And How Can It Help Me In Dynasty)?

There may come a day when minor league pitch-tracking and batted-ball data becomes publicly available. Nearly all minor league parks and many college ones are outfitted with TrackMan, which uses a 3D Doppler radar system to precisely measure location, trajectory and spin rate of pitched and batted balls. But until that type of information enters the public sphere, we have to make due with the tools at our disposal.

An initial study I conducted compared barrel rates with a variety of other FanGraphs metrics during the Statcast era, which covers the 2015 through 2020 seasons. I then performed an R-squared correlation analysis, where .5 represents a strong correlation, to see how well each one explained a hitter’s barrel rate in a given season. See the results below.

R-Squared Correlations Between Statcast Barrels And Selected Metrics

Metric Correlation with Statcast barrels
HR/FB% 0.70
HR/PA 0.69
ISO 0.66
Avg EV 0.52
Hard% 0.50
Max EV 0.38
Contact% 0.35
FB-IFFB% 0.26
FB% 0.20
GB% 0.17
Est LA StDev 0.04
IFFB% 0.01
LD% 0.01


Initially I had planned to pair a “power” metric, such as isolated slugging percentage, with a “launch angle” metric, such as line drive rate, to try to mimic how barrels are calculated. But in fact, changes in line drive rate don’t explain changes in barrel rate, producing a weak R-squared correlation of .01.

Another interesting finding was that contact percentage had a negative relationship with barrel percentage. In other words, as a hitter’s contact rate goes down, his barrel rate tends to go up, all else being equal. Similar findings have been replicated and elaborated upon by other writers.

What matters most for power hitters is the quality of contact—not the quantity—and those high-contact, high-power hitters truly are unicorns.

After looking over these options, I decided on a model with three inputs: isolated slugging percentage (ISO), home run rate per fly ball (HR/FB%) and flyball rate (FB%). 

Isolated slugging is a statistical proxy for raw power. HR/FB% is another raw power proxy, but it also catches a batter’s ability to drive the ball in the air, which is a crucial component of power production. And flyball rate is included so as to ensure that estimated barrels are catching the hitters who are able to lift the ball frequently enough to hit a good number of barrels. Elevate and celebrate, as hitters say.

With these variables isolated, a least-squares regression was used to determine a line of best fit with the historical major league barrel rate data. The resulting coefficients for the three variables then were used to create a formula for estimated barrels. The rate of MLB estimated barrels had an r-squared correlation of .759 with the rate of actual barrels. Therefore, estimated barrels describes about 75% of the variance in a hitter’s actual barrel percentage for this sample.

Adjustments For Minor League Hitters

With an estimated barrel framework and publicly available data, it is easy enough to create an estimated barrel rate per batted ball for every minor league player based on his 2019 data. However, after looking at estimated barrels for minor leaguers, there is a pretty big fly in the ointment. Unlike the major leagues, there is no singular “minor league.”

Each minor league has its own ballparks, weather patterns, hitting environments and talent levels to consider. Further complicating matters is the fact that older players tend to hit for more power, and teams tend to select for power by promoting those players who consistently drive the ball to higher levels. Another layer of complexity was the Triple-A leagues using the livelier major league ball in 2019.

To illustrate the differences in minor league levels, the table below displays the league average estimated barrel rate for each minor league level in 2019:

Estimated Barrel Rate In Each Minor League In 2019

League Level EstBarrel%
International AAA 9.3%
Pacific Coast AAA 10.2%
Eastern AA 7.6%
Southern AA 7.4%
Texas AA 8.1%
Florida State HiA 6.8%
California HiA 7.9%
Carolina HiA 7.0%
Midwest LoA 7.1%
South Atlantic LoA 7.2%
Northwest SS 6.9%
New York-Penn SS 6.6%
Appalachian R 7.8%
Pioneer R 8.3%
Arizona R 6.4%
Gulf Coast R 6.5%
Dominican Summer R 5.9%

Additionally, the individual parks within each minor league present dramatically different hitting environments. Some favor hitters and others are friendlier for pitchers.

For that reason, I made a park adjustment for each full-season park in the minor leagues in 2019, using Baseball America’s minor league park factors. I added in one extra layer—a factor I created for isolated slugging.

How Can I Use Estimated Barrels For My Dynasty Leagues?

To account for ballpark effects, I created Estimated Barrel+, or EB+, an index metric that adjusts each hitter’s estimated barrel rate for his league and home park context. A hitter with a 100 EB+ rate is estimated to record a barrel rate on batted balls at the league average rate. Each digit above or below 100 represents a one percentage point increase or decrease in the estimated barrel rate.

As an example, Rangers catcher Sam Huff’s EB+ of 290 in the South Atlantic League in 2019 means he was 190% better than the average hitter at finding the barrel.

Given the small samples and changing nature of the lower minors, EB+ for short-season leagues is adjusted for league only. Just bear in mind that there are park effects at play within those leagues that might color a player’s production.

These adjustments allow us to compare batters across different leagues, parks and seasons. So a hitter in the stingy slugging environment of Jupiter, Fla., formerly of the High-A Florida State League, can be compared with a hitter pounding the major league happy fun ball in the thin air of Las Vegas of what was the Triple-A Pacific Coast League.

Next Steps

A great next step to identify dynasty targets is to filter EB+ results in each league by “ideal age.” For our purposes, the ideal age for a player in Rookie ball is 18-and-under. For each successive level, add one year to the age, so that 19U is the ideal age for players at Low-A, 20U works for players at High-A, 21U at Double-A and 22U at Triple-A.

See the tables at the end of this feature for top 10 EB+ leaderboards at each level, filtered by ideal age.

Cautions And Caveats

Firstly, bear in mind that the Estimated Barrels+ metric is only estimating barrel production for a hitter based on publicly available statistics. Perhaps one day we will be granted access to ball-tracking data for the minor leagues—but until then, the best we can do is estimate.

Secondly, this metric is descriptive by nature. It takes a way of describing power production at the major league level and translates it to the minor leagues. It is not forward-looking by itself. I’m confident it will guide you to players with promising future production by describing their past production. But there are some additional steps which need to take place to make it a predictive measure.

Finally, this isn’t meant to be an all-encompassing measure of a prospect’s overall ability. Estimated barrels should be looked at in conjunction with scouting reports and other statistical measures. All stats need context. But for speculating on hitting prospects with big power upside, this is going to be an excellent tool.

Estimated Barrel+ For Triple-A Hitters In 2019

Hitter Team Lg Age PA EB+
HOU PCL 22 253 195
MIL PCL 22 243 170
ATL IL 22 194 149
TBR IL 22 155 148
MIL PCL 22 158 144
HOU PCL 22 536 137
CHW IL 21 223 137
LAD PCL 21 232 125
COL PCL 22 160 116
BAL IL 22 553 115

Estimated Barrel+ For Double-A Hitters In 2019

Hitter Team Lg Age PA EB+
ARI SL 21 458 166
CLE EL 21 211 151
LAD TL 21 291 144
TBR SL 21 519 138
LAA SL 20 182 135
SFG EL 19 106 132
CHW SL 21 244 130
STL TL 20 483 127
LAD TL 21 277 127
PHI EL 21 403 117

Estimated Barrel+ For High-A Hitters In 2019

Hitter Team Lg Age PA EB+
PIT FSL 20 201 200
PIT FSL 20 145 174
PHI FSL 20 478 156
TBR FSL 20 489 154
MIL CAR 20 482 144
OAK CAL 20 538 143
MIN FSL 20 131 141
MJ Melendez KCR CAR 20 419 139
PIT FSL 20 493 135
LAD CAL 20 479 133

Estimated Barrel+ For Low-A Hitters In 2019

Hitter Team Lg Age PA EB+
ARI MWL 18 102 173
PIT SAL 19 300 167
SEA SAL 19 218 161
STL MWL 19 282 148
CHC MWL 19 204 144
BOS SAL 19 493 142
SEA SAL 18 295 132
ATL SAL 18 134 125
TOR MWL 19 341 123
MIN MWL 19 118 121

Estimated Barrel+ For Short-Season Hitters In 2019

Hitter Team Lg Age PA EB+
CLE NYP 18 188 177
ARI NWL 18 189 172
SEA NWL 18 258 128
OAK NYP 18 221 122
OAK NYP 18 300 119
TEX NWL 18 100 104
CLE NYP 18 295 101
COL NWL 17 235 99
MIA NYP 18 284 94
TEX NWL 18 129 91

Estimated Barrel+ For Domestic Rookie-Level Hitters In 2019

Hitter Team Lg Age PA EB+
ATL GCL 18 116 205
SFG AZL 17 178 200
SDP AZL 17 238 177
CLE AZL 18 137 175
LAD PIO 18 279 173
CHW AZL 17 220 167
NYY GCL 17 171 165
CHW AZL 18 200 164
SDP AZL 18 195 164
STL GCL 18 162 163

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