Why Brandon Boykin is the biggest player on the Eagles roster.
I recently discussed how being a "big" player in the NFL matters, just not in ways that we think. I tested Chip Kelly’s "bigger guys beat up little guys" quip by using BMI to define "bigness" and found two significant, somewhat counter-intuitive results. During the 2013 season, a team increased its chances of winning when 1.) its offense was smaller than the opponent’s defense, and 2.) its linebackers were bigger than the opponent’s tight ends. I received a lot of constructive criticism and feedback about my use of BMI, some of which was warranted, so I took another stab at testing Chip’s "big guy" theory and found more cool results. But first, some quick points about the use of BMI from my previous post.
I chose Body Mass Index as a means to measure "bigness" for a few reasons. First, it combines two readily available measurements for every NFL player: height and weight. There are other metrics we can use to define bigness, like arm length, bone density, and muscle mass, but I couldn’t find anyone who kept those measurements for everyone (at least measurements that included players drafted before 2010). Second, BMI is familiar. Everyone who has taken a health class or been to a doctor’s office has come across it. For this reason, I intentionally avoided any reference to health or obesity because, frankly, there was no need to. The post had nothing to do with either. Third, NFL players are not representative of the general population, so, removed from that context, I ultimately decided that BMI comparisons across like-NFL bodies seemed to make sense.
However, not everyone agreed with me (#Merica). I failed to fully address my reasons for using BMI in favor of another, untested, and unproven metric (which I have used below), and failed to anticipate the resulting connotations. But whatever your feelings on BMI, it’s necessary to reiterate that, when using BMI to define bigness, there are still statistically significant findings. Granted, the findings are not easy to interpret, but that doesn’t change the fact that they exist. The interpretation is half the fun.
Moving on, I’m no stranger to creating my own metrics (see Offensive Efficiency Rate) so I tried with bigness. Rather than use BMI, I used the product of height and weight to define bigness. Here’s the actual formula:
(Player Height x Player Weight) / (Avg NFL Height x Avg NFL Weight) x 10
If you can decipher that, you’ll notice bigness values greater than 10 are above the NFL average and bigness values less than 10 are below the NFL average. More importantly, the bigness values are what you would expect to see. For example, Mychal Kendricks (5’11", 237), who was nearly two BMI units bigger than Connor Barwin (6’3", 253), has a "bigness" value of 9.17 (below the NFL average) and is smaller than Barwin, who has a value of 10.34 (above average). Using this metric, the biggest Eagle is Todd Herremans (6’6", 321) with a bigness score of 13.65, and the smallest is Brandon Boykin (5’9", 183) with a score of 6.88. Team-wise, the three biggest teams in the NFL are Baltimore (10.47), Arizona (10.45) and Tennessee (10.44), and the three smallest teams are Green Bay (9.75), Detroit (9.79), and St. Louis (9.79). The Eagles are the 22nd biggest team. If you look at this on the surface, it doesn’t seem like bigness values have much to do with team wins. And according to linear regression, indeed they don’t. There is no correlation.
Rank
Team
Bigness
Tight Ends
Linebackers
Secondary
Running Backs
Eagles
1
Baltimore Ravens
10.47
BUF
11.44
NYJ
10.55
NYJ
8.51
TAM
10.98
Todd Herremans
13.65
2
Arizona Cardinals
10.45
NOR
11.20
NWE
10.48
SEA
8.47
NWE
9.75
Jason Peters
13.59
3
Tennessee Titans
10.44
WAS
11.08
KAN
10.41
DAL
8.13
ATL
9.46
Isaac Sopoaga (traded)
12.95
4
Miami Dolphins
10.34
NWE
11.08
BAL
10.37
NOR
8.12
CHI
9.29
Lane Johnson
12.88
5
San Francisco 49ers
10.26
MIN
11.01
HOU
10.19
SFO
8.11
PIT
9.28
Evan Mathis
12.76
6
Kansas City Chiefs
10.24
JAX
10.84
ARI
10.18
TAM
8.09
MIN
9.27
Bennie Logan
12.47
7
Carolina Panthers
10.23
PHI
10.81
CLE
10.12
ATL
8.08
OAK
9.20
Cedric Thornton
12.39
8
New England Patriots
10.19
CAR
10.80
STL
10.09
KAN
8.06
NOR
9.14
Fletcher Cox
12.35
9
New York Jets
10.18
CIN
10.79
PHI
9.98
NYG
8.02
NYG
9.10
Jason Kelce
11.53
10
Cincinnati Bengals
10.16
DET
10.79
WAS
9.95
IND
8.01
SFO
9.10
Trent Cole
11.04
11
Seattle Seahawks
10.16
PIT
10.75
CIN
9.93
MIA
7.97
GNB
8.94
Brent Celek
10.81
12
San Diego Chargers
10.15
SEA
10.75
IND
9.92
ARI
7.95
WAS
8.92
Zach Ertz
10.45
13
New York Giants
10.15
CHI
10.68
SEA
9.89
CIN
7.93
IND
8.86
Connor Barwin
10.34
14
Pittsburgh Steelers
10.13
IND
10.63
PIT
9.89
TEN
7.83
NYJ
8.84
Nick Foles
10.24
15
Chicago Bears
10.13
DAL
10.61
BUF
9.87
PIT
7.82
HOU
8.76
Najee Goode
9.75
16
Oakland Raiders
10.12
DEN
10.54
GNB
9.86
JAX
7.82
SDG
8.76
James Casey
9.61
17
Indianapolis Colts
10.08
ATL
10.54
MIN
9.79
PHI
7.77
CLE
8.76
DeMeco Ryans
9.35
18
Jacksonville Jaguars
10.05
KAN
10.47
SFO
9.78
DET
7.75
JAX
8.70
Mychal Kendricks
9.17
19
Denver Broncos
10.04
SDG
10.43
MIA
9.75
BAL
7.73
KAN
8.64
Bryce Brown
8.87
20
Buffalo Bills
10.03
OAK
10.37
OAK
9.74
CAR
7.72
BAL
8.56
Riley Cooper
8.75
21
Cleveland Browns
9.99
NYG
10.36
TEN
9.74
DEN
7.69
DAL
8.52
Michael Vick
8.56
22
Philadelphia Eagles
9.95
NYJ
10.32
NOR
9.71
OAK
7.67
CAR
8.46
Jason Avant
8.36
23
Atlanta Falcons
9.95
ARI
10.31
SDG
9.65
CHI
7.65
BUF
8.33
LeSean McCoy
8.20
24
Tampa Bay Buccaneers
9.92
GNB
10.28
CAR
9.54
MIN
7.63
SEA
8.32
Nate Allen
8.16
25
Minnesota Vikings
9.92
STL
10.27
NYG
9.52
NWE
7.62
MIA
8.32
Earl Wolff
8.09
26
New Orleans Saints
9.90
SFO
10.22
DAL
9.46
BUF
7.56
CIN
8.32
Patrick Chung
8.01
27
Dallas Cowgirls
9.88
CLE
10.16
TAM
9.43
GNB
7.49
DEN
8.20
Bradley Fletcher
7.80
28
Houston Texans
9.83
BAL
10.11
DEN
9.43
CLE
7.47
PHI
8.20
Cary Williams
7.36
29
Washington Lolskins
9.80
MIA
10.02
JAX
9.29
SDG
7.42
ARI
8.13
DeSean Jackson
7.08
30
St. Louis Rams
9.79
TEN
10.01
ATL
9.26
WAS
7.31
STL
8.13
Roc Carmichael
7.06
31
Detroit Lions
9.79
HOU
9.48
DET
9.09
HOU
7.24
DET
7.96
Brandon Boykin
6.88
32
Green Bay Packers
9.75
TAM
9.12
CHI
9.00
STL
7.19
TEN
7.55
Average
10.08
10.47
9.88
7.82
8.83
9.95
Next, I used logistic regression to compare individual game outcomes to bigness values (more accurately, bigness margins) across similar, competing position groups: offenses to defenses, offensive lines to defensive lines, wide receivers to cornerbacks, linebackers to tight ends, etc. And there are only two competing position groups that yielded significant results.
Tight End versus Linebacker
This was the most statistically significant finding (p-value less than .01). On average, NFL tight ends (10.47) are larger than linebackers (9.88). Picture Denver’s TE Julius Thomas (6’5", 251 lbs) or Philly’s Zach Ertz (6’5", 249 lbs) versus Carolina’s Luke Kuechly (6’3", 242 lbs). So what kind of advantage do teams with big tight ends have? For every one bigness unit increase in a team’s tight end position group relative to its opponent’s linebacker position group in 2013, a team improved its chances of winning by 51%.
Running Back versus Secondary
I was hesitant to include this because I wasn’t sure if running backs and secondaries were relevant competing position groups. How many times during a game do running backs and corners/safeties actually interact? Not exactly sure (maybe more often than I think?), but the result is still statistically significant (p-value less than .05), so here it is. For every one bigness unit increase in a team’s secondary relative to its opponent’s running backs, that team improved its chances of winning by 30%. On average, NFL secondaries are relatively small (7.82 bigness units) and running backs are slightly larger (8.82 bigness units). Picture Bradley Fletcher (6’1", 196 lbs) and LeSean McCoy (5’10", 215 lbs), both average-sized or below with respect to their position groups. If McCoy breaks free into the secondary, who would you rather have available to stop him, Fletcher or Seattle’s Kam Chancellor(6’3", 232 lbs)? Trick question though… no one can stop Shady!
So what about Brandon Boykin?
That last example leads into a nice point. Obviously, for shits and giggles, I’m taking what Chip Kelly said quite literally. In the NFL, big people don’t always beat up little people. Yes, there do seem to be advantages for bigger tight ends and bigger secondaries, but there is no causation here. Big players may not breed team success any more than team success breeds bigger players. At some point, talent, speed, quickness, intelligence, and technique come into play and limit any advantages afforded by size alone. At some point, David beats Goliath. Which is why, with six interceptions (one returned for a touchdown), two forced fumbles, and of course that game-saving interception against Dallas, Brandon Boykin(g) might be the biggest player on the Eagles roster.
Play big or go home.