Point Differential: Which
Leagues are Fairer?
Jon Green and Nat Enelow
Introduction
The most basic principle in sports is that if you score more
points than the other team, you win. Is that always true,
though? Do the different ways in which sports leagues
determine who goes to the playoffs leave the door open for
lesser teams to go to the postseason while more dominant
teams are left out?
Methodology and Parameters
Data on team performance and playoff qualification is readily
available on ESPN.com. We've taken the data from the most
recently completed season from each league to analyze.
Since it can be assumed that there is a relationship between
points and success (if more points didn't equal more success,
no one would play sports), we will be looking for small changes
in the relationship between the two.
NHL Overview
EAST
WEST
TEAM
W
L
OT
PTS
DIFF
RESIDIFF
RESPTS
TEAM
W
L
OT
PTS
DIFF
RESIDIFF RESPTS
1
z -WSH
54
15
13
121
85
9.2382
-0.531696
1
z - SJ
51
20
11
113
49
-5.8379
3.96173
2
y - NJ
48
27
7
103
31
2.3169
0.208440
2
y -CHI
52
22
8
112
62
9.7776
-1.54979
3
y - BUF
45
27
10
100
28
7.1633
-1.75044
3
y - VAN
49
28
5
103
50
21.3169
-6.38531
4
x - PIT
47
28
7
101
20
-3.4522
2.02588
4
x - PHX
50
25
7
107
23
-16.1450
6.98476
5
x -OTT
44
32
6
94
-13
-18.1438
6.47818
5
x -DET
44
24
14
102
13
-13.0676
5.45515
6
x - BOS
39
30
13
91
6
8.7027
-3.11557
6
x - LA
46
27
9
101
22
-1.4522
1.33180
7
x - PHI
41
35
6
88
11
21.5491
-7.85077
7
x - NSH
47
29
6
100
0
-20.8367
7.96667
8
x -MTL
39
33
10
88
-6
4.5491
-1.95110
8
x - COL
43
30
9
95
11
3.2407
-0.850769
9
e - NYR
38
33
11
87
4
17.1646
-6.42149
9
e - STL
40
32
10
90
2
7.3181
-2.72741
10
e - ATL
35
34
13
83
-22
1.6265
-1.39846
10
e - CAL
40
32
10
90
-6
-0.6819
0.0489040
11
e - CAR
35
37
10
80
-26
5.4730
-3.01030
11
e -ANA
39
32
11
89
-13
-5.0664
1.47818
12
e - TB
34
36
12
80
-43
-11.5270
2.88937
13
e - DAL
37
31
14
88
-17
-6.4509
1.86634
13
e - NYI
34
37
11
79
-42
-7.9116
1.54233
13
e –MIN
38
36
8
84
-27
-5.9890
1.33673
14
e - FLA
32
37
13
77
-36
3.3194
-2.53991
14
e - CLB
32
35
15
79
-43
-8.9116
1.88937
15
e -TOR
30
38
14
74
-53
-5.8341
0.359764
15
e - EDM
27
47
8
62
-70
8.5516
-5.74056
z- Conference Winner
y- Division Winner
x- Made Playoffs
e- Missed Playoffs
NHL Scatterplot
R-Squared = 90.8%
Max Diff = 85
Min Diff = -70
StDevDiff = 35.5
It is worth noting
that eight teams
had residuals of
+/- 10 goals.
DIFF = - 241 + 2.62 PTS
PTS = 92.0 + 0.347 DIFF
Overview - NBA
Eastern Conference
Team
W
Western Conference
L
PCT
DIFF
RESIDIFF
RESWIN Team
W
L
PCT
DIFF
RESDIFF RESWIN
1
2
3
z - CLE 61
y - ORL 59
x - ATL 53
21
23
29
0.744
0.720
0.646
6.5
7.5
4.7
-0.361
1.3130
0.5944
1
2.0170
-2.7498
2
-1.0037
3
z - LAL
57
25
0.695
4.7
-0.7837
2.9969
y - DAL
55
27
0.671
2.7
-2.1087
6.5301
x - PHX
54
28
0.659
4.9
0.4287
-0.5563
4
y - BOS 50
32
0.610
3.6
0.5070
y - DEN 53
29
0.646
4.1
-0.0055
0.6569
5
6
7
x - MIA 47
x - MIL 46
x - CHA 44
35
36
38
0.573
0.561
0.537
2.3
1.7
1.5
0.2476
-0.0147
0.4602
-0.9598
4
-0.3632
5
0.2967
6
-1.1499
7
x - UTA
53
29
0.646
5.3
1.1944
-2.6630
x - POR 50
32
0.610
3.3
0.2070
-0.1298
x - SAN 50
32
0.610
5.1
2.0070
-5.1097
8
9
x - CHI
TOR
41
40
41
42
0.500
0.488
-1.6
-1.8
-1.599
-1.461
4.4265
8
3.9799
9
x - OKL
50
32
0.610
3.5
0.4070
-0.6831
HOU
42
40
0.512
-0.3
-0.6365
1.8299
10
11
IND
NY
32
29
50
53
0.390
0.354
-3.0
-3.8
0.094
0.3074
10
-0.7001
-1.4868
11
MEM
40
42
0.488
-1.5
-1.1615
3.1499
NO
37
45
0.451
-2.5
-1.1208
2.9165
12
13
DET
PHI
27
27
55
55
0.329
0.329
-5.1
-3.9
-0.2894
0.9106
0.1097
12
-3.2102
13
LAC
29
53
0.354
-6.4
-2.2925
5.7063
GLD
26
56
0.317
-3.6
1.5481
-5.0402
14
15
WSH
NJ
26
12
56
70
0.317
0.146
-4.8
-9.1
0.3481
0.8577
-1.720
14
-3.823
15
SCR
25
57
0.305
-4.4
1.0856
-3.8269
MIN
15
67
0.183
-9.6
-0.6829
0.5594
z- Conference Winner
y- Division Winner
x- Made Playoffs
Scatterplot - NBA
R-Squared = 94.9%
Max Diff = 7.5
Min Diff = -9.6
StDevDiff = 4.7042
In the NBA, every team in
the playoffs had a positive
differential (except one),
and every team that
missed the playoffs had a
negative differential.
PCT = .50 +.0337 DIFF
Diff = - 14.1 + 28.1 PCT
MLB Overview
AL
NL
TEAM
W
L
PCT
DIFF
RESDIFF
RESWIN
TEAM
W
L
PCT
DIFF
RESDIFF
RESWIN
1
Z- TB
96
66
0.593
153
-0.401114
0.741387
1
Z-PHI
97
65
0.599
132
-31.3051
3.69845
2
Y - NYY
95
67
0.586
166
24.1535
-1.47013
2
X- SFG
92
70
0.568
114
1.86533
0.375936
3
X- MIN
94
68
0.580
110
-21.9426
2.74871
3t
X- CIN
91
71
0.562
105
2.76927
0.214677
4
X-TEX
90
72
0.556
100
7.67322
-0.319355
3t
Y- ATL
91
71
0.562
109
6.76927
-0.158097
5
BOS
89
73
0.549
74
-6.77218
1.10368
5
SDG
90
82
0.556
84
-8.32678
1.17174
6
CHISOX
88
74
0.543
48
-22.8682
2.52671
6
STL
86
76
0.531
95
43.9397
-3.85339
7
TOR
85
77
0.525
27
-14.1564
1.48377
7
COL
83
79
0.512
563
33.3022
-2.93926
8t
DET
81
81
0.500
8
8.11004
-0.745548
8t
FLA
80
82
0.494
2
12.0140
-1.18639
8t
OAK
81
81
0.500
37
37.1100
-3.44816
8t
LAD
80
82
0.494
-25
-14.9860
1.32984
10
LAA
80
82
0.494
-21
-10.9860
0.957065
10
NYM
79
83
0.488
4
23.9179
-2.37277
11
CLE
69
93
0.426
-106
16.2587
-2.12148
11
MIL
77
85
0.475
-54
-12.6235
1.03245
12
KC
67
95
0.414
-169
-26.9334
1.74971
12
HOU
76
86
0.469
-118
-66.7196
5.99684
13
BAL
66
96
0.407
-172
-18.3788
1.02929
13
CHICUB
75
87
0.463
-82
-20.8156
1.64187
14
SEA
61
101
0.377
-185
18.1409
-2.75919
14
WSH
69
93
0.426
-87
35.2587
-3.89216
15
ARI
65
97
0.401
-123
40.5251
-4.53719
16
PIT
57
105
0.352
-279
-34.5926
2.00100
z- Won League
x- Won Division
y- Wild Card
MLB
R-Squared = 95.0%
Max Diff = 166
Min Diff = -279
StDevDiff = 115.1
It is worth noting that every
team with a run differential
of 100+ made the playoffs.
PCT = 0.500 + 0.000575 DIFF
DIFF = - 825 + 1651 PCT
Overview - NFL
NFC
AFC
* - #1 Seed
z- Won Division
y- Wild Card
Scatterplot - NFL
R-Squared = 82%
Max Diff = 205
Min Diff = -212
StDevDiff = 96.98
The NFL had the lowest R2
value of all of the leagues
we examined.
PCT = 0.50002 + 0.00174 DIFF
DIFF = - 235 + 469 PCT
Case Study - San Diego Chargers
-The 2010 San Diego Chargers had
the NFL's top ranked offense and
defense statistically, which allowed
them to finish the season with a point
differential of +119, 5th best in the
league.
-Despite their statistical dominance,
they managed a record of only 9-7, and
fell just short of making the playoffs.
- A team with a point differential of
+119 is expected to win 11 games.
- The Chargers are a perfect example
of why a positive point differential alone
does not make a team great. The New
York Jets were only +63 on the
season, but finished 11-5 and made it
all the way to the AFC championship
game.
Case Study - 2010 Nashville Predators
-The Nashville Predators were the 7th seed in the Western
Conference.
-100 Points were achieved with a goal differential of 0.
- A team that earns 100 points is expected to have a goal
differential of around +21.
-A team with a goal differential of 0 is expected to earn 92
points.
-Had Nashville only gotten their expected 92 points, they would
have finished behind Colorado and out of the playoffs.
-Surprisingly, Nashville did not benefit from the NHL's scoring
system, which awards points for losing in overtime. They only
had six overtime losses.
Conclusion
There seems to be a pattern between season length and the
predictive value of point differential. The MLB with its 162game season was the most predictive. The NFL was the least,
and it uses a 16-game season. The NHL also appears to have
some unfairness in its point system, which is why it is less
predictive than the NBA despite equal season-lengths.
Overall, there is still a strong correlation between scoring more
points and winning more games. However, there is still room
for scrappier teams to "win ugly."
Sources
ESPN.com
http://www.helium.com/items/1332713-nhl-points-system