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How to Detect an Early Bust: FB% and It’s Importance

Before I get into how to detect an early bust in Fantasy Baseball drafts, I thought I’d share a story.

I’m at a weird age in my life. A few years ago I walked across a college campus and the girls that would flirt with me, if they weren’t my age, were at least close enough in age for it to be socially acceptable.

Fast Forward a Few Years: I walked into Target a couple months ago on my lunch break, looked up, and caught a mother and daughter, unbeknownst to each family member, as they checked me out: so weird.

I’m at weird age; I’m now old enough to where it’s socially acceptable for women of all ages to check me out.

It’s the same way for people from all walks of life. This reminds me of the study that looked at how often bystanders crossed the street, while they were at a yield sign and there was no through traffic. Or if they were prompted to do so by a homeless person, as opposed to a man in a suit. It’s safe to say that bystanders followed the man in the suit, but not the homeless person. (I can’t remember the name of the study or who conducted it, but I’d appreciate anyone who does know, if they could leave a comment about it). This video evokes the same sentiment:

The point is that appearances, even though they shouldn’t, determine how (some, not all) people approach you.

The same is true for Fantasy Baseball, but for better reasons.

Correlation Between FB% and Batter Outcome

Pitchers approach players that hit for more power differently. It’s a fact.

Since 2002, FB% (i.e. what percent of the time a player saw a fastball) had a -0.33r (chart below) with ISO (isolated power), which is a strong inverse relationship.


It makes sense — the more power a player has, the less you want to give him a pitch he can do damage with.

To take this a step further, it also makes sense that FB% has a -.42r (graph below) with K% (strikeout percentage), because players that hit for power, as a generalization, strikeout more.


A lot of this is old news. Eno Sarris has looked at potential breakouts based off of changes in FB%, and Robert Arthur has done the seminal research when it comes to the importance of a pitcher’s approach to hitters.

Importance in the Change of FB%

For my research, I looked at all qualified hitters that played in two consecutive seasons from 2002 to 2014. I then calculated the correlation between FB% from one season to next for that sample.

What I found is that FB% for hitters is very consistent from year to year. So much so, that it has one of the highest year-to-year correlations, at a .86r, of any metric for hitters! (See the chart below for the work that Bill Petti has done on year-to-year correlations for hitting metrics).

Bill Petti's research done on year to year correlation for hitting metrics done on Beyond the Box Score

Bill Petti’s research done on year to year correlation for hitting metrics done on Beyond the Box Score

This suggests that once a hitter’s FB% changes, you can take this to be a meaningful variation.

Let’s look at the list below.

The fourth column shows the player’s FB% differential from 2013 to 2014. And the fifth column shows their difference in ISO from 2013 to 2014.

The list below is sorted to show the players that had the highest increase in FB% from 2013 to 2014 at the top, and, as you can see, the players who saw the highest increase in FB% saw some pretty drastic losses to their total ISO.

SeasonNameTeamFB% 13-14 (DIFF)ISO 13-14 (DIFF)
2014Ryan HowardPhillies9%-0.079
2014Curtis GrandersonMets6%-0.099
2014Allen Craig- - -6%-0.042
2014Ryan BraunBrewers5%-0.089
2014Hanley RamirezDodgers5%-0.015
2014Jason HeywardBraves5%-0.097
2014Robinson CanoMariners5%-0.063
2014Jean SeguraBrewers5%-0.049
2014Justin UptonBraves5%0.02
2014Evan LongoriaRays4%-0.079
2014Jose ReyesBlue Jays4%-0.035
2014Adeiny HechavarriaMarlins4%0.008
2014Andrelton SimmonsBraves4%-0.062
2014Ben ZobristRays4%-0.004
2014Mike TroutAngels4%0.04
2014Domonic BrownPhillies4%-0.108
2014Casey McGeheeMarlins3%-0.053
2014Todd FrazierReds3%0.013
2014Jose BautistaBlue Jays3%0
2014Brian McCannYankees3%-0.021
2014Asdrubal Cabrera- - -3%-0.013
2014Zack CozartReds3%-0.048
2014Dustin PedroiaRed Sox3%-0.016
2014B.J. UptonBraves3%-0.083
2014James LoneyRays3%-0.041
2014Matt CarpenterCardinals3%-0.06
2014Justin MorneauRockies2%0.025
2014Jimmy RollinsPhillies2%0.054
2014Freddie FreemanBraves2%-0.008
2014Jed LowrieAthletics2%-0.05
2014David FreeseAngels2%0.004
2014Jonathan LucroyBrewers2%-0.011
2014Gerardo Parra- - -2%-0.027
2014Matt KempDodgers2%-0.042
2014Starling MartePirates1%0.001
2014Dustin AckleyMariners1%0.051
2014Chris CarterAstros1%0.037
2014Jay BruceReds1%-0.06
2014Ben ReverePhillies1%0.006
2014Giancarlo StantonMarlins1%0.036
2014Adam LaRocheNationals1%0.03
2014Derek JeterYankees1%-0.056
2014Coco CrispAthletics1%-0.066
2014Chase UtleyPhillies1%-0.053
2014Adrian GonzalezDodgers1%0.038
2014Hunter PenceGiants1%-0.032
2014Desmond JenningsRays1%-0.027
2014Jason KipnisIndians1%-0.078
2014Adrian BeltreRangers1%-0.025
2014Chase Headley- - -1%-0.02
2014J.J. HardyOrioles1%-0.066
2014Adam Dunn- - -0%-0.027
2014Dayan ViciedoWhite Sox0%-0.014
2014David OrtizRed Sox0%0
2014Yunel EscobarRays0%-0.028
2014Shin-Soo ChooRangers0%-0.046
2014Chris JohnsonBraves0%-0.038
2014Kurt SuzukiTwins0%-0.053
2014Aaron HillDiamondbacks0%-0.096
2014Neil WalkerPirates0%0.028
2014Carlos SantanaIndians0%0.009
2014Denard SpanNationals0%0.013
2014Brandon CrawfordGiants0%0.029
2014Howie KendrickAngels0%-0.038
2014Jhonny PeraltaCardinals-1%0.035
2014Jayson WerthNationals-1%-0.051
2014Austin Jackson- - --1%-0.055
2014David WrightMets-1%-0.081
2014Elvis AndrusRangers-1%0.009
2014Matt DominguezAstros-1%-0.047
2014Alex RiosRangers-1%-0.036
2014Anthony RizzoCubs-1%0.054
2014Jose AltuveAstros-1%0.032
2014Albert PujolsAngels-1%-0.037
2014Erick AybarAngels-1%-0.011
2014Seth SmithPadres-1%-0.026
2014Omar InfanteRoyals-1%-0.059
2014Eric HosmerRoyals-1%-0.019
2014Yoenis Cespedes- - --1%-0.012
2014Brett GardnerYankees-1%0.023
2014Nori AokiRoyals-1%-0.009
2014Nelson CruzOrioles-1%0.054
2014Andrew McCutchenPirates-1%0.038
2014Garrett JonesMarlins-1%-0.077
2014Marlon ByrdPhillies-1%-0.039
2014Pablo SandovalGiants-1%-0.003
2014Joe MauerTwins-1%-0.058
2014Ian DesmondNationals-1%0.002
2014Ian KinslerTigers-1%0.009
2014Miguel CabreraTigers-1%-0.077
2014Alcides EscobarRoyals-1%0.026
2014Mark TeixeiraYankees-2%-0.042
2014Edwin EncarnacionBlue Jays-2%0.017
2014Alexei RamirezWhite Sox-2%0.039
2014Josh DonaldsonAthletics-2%0.002
2014Adam JonesOrioles-2%-0.02
2014Matt HollidayCardinals-2%-0.021
2014Dexter FowlerAstros-2%-0.052
2014Torii HunterTigers-2%-0.002
2014Trevor PlouffeTwins-2%0.027
2014Chris DavisOrioles-2%-0.139
2014Aramis RamirezBrewers-2%-0.098
2014Miguel MonteroDiamondbacks-2%-0.025
2014Melky CabreraBlue Jays-3%-0.007
2014Daniel MurphyMets-3%-0.015
2014Martin Prado- - --3%-0.004
2014Jacoby EllsburyYankees-3%0.02
2014Leonys MartinRangers-3%-0.035
2014Carlos GomezBrewers-3%-0.029
2014Buster PoseyGiants-3%0.023
2014Alex GordonRoyals-4%0.009
2014Brandon MossAthletics-4%-0.063
2014Victor MartinezTigers-4%0.101
2014Nick MarkakisOrioles-4%0.026
2014Kyle SeagerMariners-4%0.02
2014Billy ButlerRoyals-4%-0.017
2014Michael BrantleyIndians-4%0.066
2014Brian DozierTwins-4%0.004
2014Starlin CastroCubs-5%0.044
2014Salvador PerezRoyals-6%0.003
2014Alejandro De Aza- - --7%-0.008

What might make one more pessimistic about the players at the top of the list above, at least as far as the decline of their ISO goes, is that the players that saw the largest increase in FB% from 2012-2013 (chart below) generally continued on a downward trend in 2014. Out of the top 30 players that had the largest increase in FB% in 2013, 21 of those 30 saw a decrease in their ISO in 2013, and 15 out of the 21 continued to see a diminished ISO in 2014 (the bar graph illustrates this visually).

NameFB% 12-13 (DIFF)ISO 12-13 (DIFF)ISO 13-14 (DIFF)
Alfonso Soriano7%-0.003-0.088
Andre Ethier6%-0.025-0.031
Marco Scutaro6%-0.026-0.072
Adam Lind5%0.021-0.05
Starlin Castro5%-0.0450.044
Carlos Gomez5%0.12-0.029
Chris Davis4%0.117-0.139
Mitch Moreland4%0.051-0.104
Adam LaRoche4%-0.0720.03
Buster Posey4%-0.0570.023
Michael Bourn3%-0.020.007
Brandon Phillips3%-0.013-0.029
Chris Johnson3%-0.034-0.038
Carlos Beltran3%-0.032-0.026
Nate McLouth3%-0.038-0.076
Martin Prado3%-0.001-0.004
Joey Votto3%-0.036-0.031
Matt Holliday3%-0.012-0.021
Nick Markakis3%-0.0370.026
Robinson Cano2%-0.036-0.063
Daniel Murphy2%0.017-0.015
Ian Desmond2%-0.0450.002
Justin Upton2%0.0510.02
Eric Hosmer2%0.019-0.019
Darwin Barney2%-0.0040.005
Troy Tulowitzki2%-0.0130.034
Adrian Beltre2%-0.047-0.025
Denard Span2%-0.010.013
Jon Jay2%-0.032-0.02
Allen Craig2%-0.073-0.042
Justin Morneau2%-0.020.025
Mike Moustakas2%-0.040.018
Nori Aoki2%-0.06-0.009
Yoenis Cespedes2%-0.012-0.012
Nick Swisher1%-0.024-0.055
Marlon Byrd1%0.084-0.039
Adrian Gonzalez1%0.0040.038
Carlos Santana1%0.0190.009
Ryan Zimmerman1%-0.006-0.022
David Freese1%-0.0550.004
Prince Fielder1%-0.037-0.065
Edwin Encarnacion1%-0.0150.017
Neil Walker1%0.0210.028
Billy Butler1%-0.073-0.017
Jay Bruce1%-0.047-0.06
Jose Bautista1%-0.0670
Alex Rios1%-0.058-0.036
Zack Cozart1%-0.026-0.048
Alexei Ramirez1%-0.0030.039
Hunter Pence1%0.028-0.032
Asdrubal Cabrera1%0.006-0.013
Austin Jackson0%-0.034-0.055
Paul Konerko0%-0.0770
Alejandro De Aza0%0.012-0.008
Erick Aybar0%-0.015-0.011
Josh Hamilton0%-0.11-0.031
Jose Altuve0%-0.0290.032
Giancarlo Stanton0%-0.0440.036
A.J. Pierzynski0%-0.07-0.067
Pedro Alvarez0%0.017-0.067
Mike Napoli0%-0.007-0.052
Paul Goldschmidt0%0.045-0.008
Shane Victorino0%0.029-0.043
Alberto Callaspo0%0.001-0.043
Ian Kinsler0%-0.030.009
Shin-Soo Choo0%0.019-0.046
Mark Trumbo0%-0.003-0.039
Michael Brantley-1%-0.0020.066
Miguel Cabrera-1%0.011-0.077
Victor Martinez-1%-0.0120.101
Howie Kendrick-1%0.029-0.038
Michael Cuddyer-1%0.0220.049
Chase Utley-1%0.022-0.053
Jimmy Rollins-1%-0.080.054
Chase Headley-1%-0.062-0.02
Elvis Andrus-1%-0.0320.009
Jacoby Ellsbury-1%-0.1020.02
Jayson Werth-1%0.057-0.051
Pablo Sandoval-1%-0.001-0.003
Mark Reynolds-1%-0.0350.025
Yadier Molina-1%-0.028-0.054
J.J. Hardy-1%0.019-0.066
Kendrys Morales-1%-0.023-0.051
Ryan Doumit-1%-0.038-0.027
Justin Smoak-1%0.027-0.037
David Ortiz-1%0.0090
Jason Kipnis-1%0.046-0.078
Alcides Escobar-2%-0.0320.026
Ben Zobrist-2%-0.075-0.004
Dan Uggla-2%0.019-0.119
Brett Gardner-2%0.0330.023
Torii Hunter-2%0.023-0.002
Andrew McCutchen-2%-0.0360.038
Adam Dunn-2%-0.04-0.027
Dustin Pedroia-2%-0.046-0.016
Ichiro Suzuki-3%-0.026-0.025
Adam Jones-3%-0.01-0.02
Russell Martin-3%0.072-0.011
James Loney-3%0.003-0.041
Desmond Jennings-3%0.018-0.027
Freddie Freeman-3%-0.015-0.008
Coco Crisp-4%0.025-0.066
Kyle Seager-4%0.0030.02
Joe Mauer-4%0.026-0.058
Alex Gordon-4%-0.0040.009
Mike Trout-4%-0.0040.04
Matt Wieters-4%-0.0040.01
Evan Longoria-5%-0.021-0.079
Yunel Escobar-5%0.019-0.028
Gregor Blanco-5%0.0260.031


Work needs to be done to see how long it takes for hitter FB% to stabilize, and once it does, we’ll be able to see how long we should wait before we should worry about a player’s deflated power potential.

Feature Image Courtesy of Jim Leuenberger

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