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
22-And-Under

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
21-And-Under

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
20-And-Under

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
19-And-Under

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
18-And-Under

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
18-And-Under

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